Method and apparatus for diversity-based data transmission in mobile communication system

ABSTRACT

The present disclosure relates to a communication technique for convergence of IoT technology and a 5G communication system for supporting a higher data transfer rate beyond a 4G system, and a system therefor. The present disclosure can be applied to intelligent services (e.g., smart homes, smart buildings, smart cities, smart or connected cars, health care, digital education, retail business, and services associated with security and safety) on the basis of 5G communication technology and IoT-related technology. The present invention relates to an indication method for indicating a diversity-based data transmission method to a terminal by a base station, and a related-based transmission method.

PRIORITY

This application is a National Phase Entry of PCT InternationalApplication No. PCT/KR2018/003907 which was filed on Apr. 3, 2018, andclaims priority to Korean Patent Application Nos. 10-2017-0043247 and10-2017-0093806, which were filed on Apr. 3, 2017 and Jul. 24, 2017,respectively, the content of each of which is incorporated herein byreference.

TECHNICAL FIELD

The disclosure relates to a wireless communication system and more,particularly to, a method and an apparatus for transmitting adiversity-based signal, a method and an apparatus for configuring ademodulation reference signal (DMRS), and a method and an apparatus forconfiguring a reference signal to measure a channel state.

BACKGROUND ART

In order to meet wireless data traffic demands that have increased after4G communication system commercialization, efforts to develop animproved 5G communication system or a pre-5G communication system havebeen made. For this reason, the 5G communication system or the pre-5Gcommunication system is called a beyond 4G network communication systemor a post LTE system. In order to achieve a high data transmission rate,an implementation of the 5G communication system in a mmWave band (forexample, 60 GHz band) is being considered. In the 5G communicationsystem, technologies such as beamforming, massive MIMO, full dimensionalMIMO (FD-MIMO), array antenna, analog beam-forming, and large scaleantenna are being discussed as means to mitigate a propagation path lossin the mm Wave band and increase a propagation transmission distance.Further, the 5G communication system has developed technologies such asan evolved small cell, an advanced small cell, a cloud radio accessnetwork (RAN), an ultra-dense network, device to device communication(D2D), a wireless backhaul, a moving network, cooperative communication,coordinated multi-points (CoMP), and received interference cancellationto improve the system network. In addition, the 5G system has developedadvanced coding modulation (ACM) schemes such as hybrid FSK and QAMmodulation (FQAM) and sliding window superposition coding (SWSC), andadvanced access technologies such as filter bank multi carrier (FBMC),non orthogonal multiple access (NOMA), and sparse code multiple access(SOMA).

Meanwhile, the Internet has been evolved to an Internet of things (IoT)network in which distributed components such as objects exchange andprocess information from a human-oriented connection network in whichhumans generate and consume information. An Internet of everything (IoE)technology in which a big data processing technology through aconnection with a cloud server or the like is combined with the IoTtechnology has emerged. In order to implement IoT, technical factorssuch as a sensing technique, wired/wireless communication, networkinfrastructure, service-interface technology, and security technologyare required, and research on technologies such as a sensor network,machine-to-machine (M2M) communication, machine-type communication(MTC), and the like for connection between objects has recently beenconducted. In an IoT environment, through collection and analysis ofdata generated in connected objects, an intelligent Internet technology(IT) service to create a new value for peoples' lives may be provided.The IoT may be applied to fields, such as a smart home, smart building,smart city, smart car, connected car, smart grid, health care, smarthome appliance, or high-tech medical service, through the convergence ofthe conventional Information technology (IT) and various industries.

Accordingly, various attempts to apply the 5G communication system tothe IoT network are made. For example, 5G communication technologiessuch as a sensor network, machine-to-machine (M2M) communication, andmachine-type communication (MTC) are implemented using beamforming,MIMO, and array-antenna schemes. The application of a cloud RAN as thebig data processing technology may be an example of convergence of the5G technology and the IoT technology.

In a newly researched 5^(th) generation mobile communication system (ornew radio (NR)), research on application of a diversity scheme to uplinktransmission of the UE is conducted. Further, transmission of areference signal is needed to demodulate a signal through channelestimation, and a demodulation reference signal (DMRS) which can beconfigured to support an increased channel bandwidth and variousnumerologies is under consideration in the NR system. In addition, inorder to reduce overhead of a channel status information referencesignal (CSI-RS), aperiodic CSI-RS transmission and a configurationmethod according thereto have been researched.

DISCLOSURE OF INVENTION Technical Problem

The disclosure proposes a method of transmitting a signal through adiversity scheme and a method of indicating diversity transmission inuplink.

The disclosure proposes a method of generating a DMRS sequencereflecting various considerations of a 5G wireless communication system,a method of mapping a DMRS sequence, and a detailed parameter accordingthereto.

The disclosure proposes a method of transmitting and configuring anaperiodic CSI-RS and a method and an apparatus for determining abandwidth for aperiodic CSI-RS measurement in a wireless communicationsystem.

Solution to Problem

In accordance with an aspect of the disclosure, a method of transmittinga channel state information reference signal (CSI-RS) by a base station(BS) in a wireless communication system is provided. The methodincludes: transmitting CSI-RS configuration information including aconfiguration of CSI-RS resources; transmitting downlink controlinformation including triggering information indicating at least oneCSI-RS resource among the CSI-RS resources to a user equipment (UE); andtransmitting a CSI-RS according to the at least one CSI-RS resource tothe UE. The downlink control information may further include informationindicating a bandwidth of the at least one CSI-RS resource, thebandwidth indication information indicates one of a CSI-RS bandwidthconfigured by a higher layer and a predefined bandwidth, the predefinedbandwidth may be a bandwidth part, a UE bandwidth, or a systembandwidth, and the downlink control information may further includeinformation indicating a bandwidth of a zero power (ZP) CSI-RS.

In accordance with another aspect of the disclosure, a method ofreceiving a channel state information reference signal (CSI-RS) by auser equipment (UE) in a wireless communication system is provided. Themethod includes: receiving CSI-RS configuration information including aconfiguration of CSI-RS resources from a base station (BS); receivingdownlink control information including triggering information indicatingat least one CSI-RS resource among the CSI-RS resources from the BS; andreceiving a CSI-RS according to the at least one CSI-RS resource fromthe BS.

In accordance with another aspect of the disclosure, a base station (BS)for transmitting a channel state information reference signal (CSI-RS)in a wireless communication system is provided. The BS includes: atransceiver; and a controller configured to perform control to transmitCSI-RS configuration information including a configuration of CSI-RSresources, transmit downlink control information including triggeringinformation indicating at least one CSI-RS resource among the CSI-RSresources to a user equipment (UE), and transmit a CSI-RS according tothe at least one CSI-RS resource to the UE, the controller beingconnected to the transceiver.

In accordance with another aspect of the disclosure, a user equipment(UE) for receiving a channel state information reference signal (CSI-RS)in a wireless communication system is provided. The UE includes: atransceiver; and a controller configured to perform control to receiveCSI-RS configuration information including a configuration of CSI-RSresources from a base station (BS), receive downlink control informationincluding triggering information indicating at least one CSI-RS resourceamong the CSI-RS resources from the BS, and receive a CSI-RS accordingto the at least one CSI-RS resource from the BS, the controller beingconnected to the transceiver.

Advantageous Effects of Invention

According to an embodiment of the disclosure, it is possible toefficiently use radio resources according to a method of transmitting asignal through an uplink diversity scheme proposed by the disclosure anda method of configuring the signal when uplink transmission isperformed. According to an embodiment of the disclosure, it is possibleto effectively demodulate a signal and efficiently use radio resourcesthrough various DMRS structures, a DMRS sequence mapping method, and aDMRS sequence initialization method according to the disclosure.According to an embodiment of the disclosure, it is possible to improvetransmission efficiency of a reference signal and expect an increase insystem throughput by a base station and a UE including a plurality ofantennas.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates the basic structure of a time/frequency region whichis a radio resource region in which the data or control channel istransmitted in downlink of the LTE system;

FIG. 2 illustrates the basic structure of a time-frequency region whichis a radio resource region in which the data or control channel istransmitted in uplink of the LTE system according to the prior art;

FIGS. 3 and 4 illustrate examples of allocating data for eMBB, URLLC,and mMTC which are services considered in the system to frequency-timeregions;

FIG. 5 illustrates an example of uplink transmission through dynamicbeamforming and semi-dynamic beamforming;

FIG. 6 illustrates an example in which the UE and the base stationtransmit a reference signal in order to acquire channel stateinformation required for uplink transmission in the NR system;

FIG. 7 illustrates an example of allocating resources for uplinktransmission and applying subband precoding;

FIG. 8 illustrates a method of applying different precodings to REsproposed by the present embodiment on the assumption that two DMRS portsare used;

FIG. 9 illustrates an example in which RE-specific mapping ofapplication of a precoder to each symbol is different to increase adiversity gain;

FIG. 10 illustrates a comparison between performance of the precodercycling method illustrated in FIG. 8 and the precoder cycling methodillustrated in FIG. 9;

FIG. 11 illustrates an example of applying another precoding in units oftime resources based on the assumption that the number of DMRS portswhich is the same as the number of transmitted ranks are used;

FIG. 12 illustrates an example of precoder cycling in units of timebased on the assumption that DMRSs are transmitted in one entire symbol;

FIG. 13 illustrates an example in which different precodings are appliedto RBs or PRGs based on the assumption that two DMRS ports are used;

FIG. 14A illustrates an example of using the codebook for thediversity-based transmission;

FIG. 14B illustrates an example of an operation for activating SRScandidate resources through the MAC CE and actually activating SRScandidate resources through DCI;

FIG. 15 illustrate time and frequency resources used to transmit uplinkdata by a plurality of UEs;

FIG. 16 is a block diagram illustrating an internal structure of the UEaccording to an embodiment of the disclosure;

FIG. 17 is a block diagram illustrating an internal structure of thebase station according to an embodiment of the disclosure;

FIG. 18 illustrates the basic structure of a time-frequency region whichis a radio frequency region in which a data or control channel istransmitted in downlink of the LTE system;

FIG. 19 illustrates the basic structure of a time-frequency region whichis a radio frequency region in which a data or control channel istransmitted in uplink of the LTE system;

FIG. 20 illustrates radio resources of one RB which is the minimum unitof scheduling in downlink of the LTE system;

FIG. 21 illustrates an example of a method of generating a DMRS;

FIG. 22A illustrates an example of the unit DMRS structure proposed bythe disclosure;

FIG. 22B illustrates an example in which DC subcarriers are arrangedaccording to the DMRS structure proposed by the disclosure;

FIG. 23 illustrates an example of a method of mapping antenna ports tothe unit DMRS structure proposed by FIG. 22A;

FIG. 24 illustrates an example of a method of mapping a larger number ofantenna ports to the unit DMRS structure proposed by FIG. 23;

FIG. 25 illustrates the location of the front-loaded DMRS in the case inwhich a slot length is 7 or 14 OFDM symbols;

FIG. 26 illustrates the location at which the extended DMRS istransmitted in the case in which the slot length is 7 or 14 OFDMsymbols;

FIG. 27 illustrates an example of a two-step resource allocation method;

FIG. 28 illustrates an example of a pattern available in type 1according to the antenna port mapping method;

FIG. 29 illustrates an example of a pattern available in type 2according to the antenna port mapping method;

FIG. 30 illustrates an example of DMRS transmission for the type 1 DMRSpattern;

FIG. 31 illustrates the operations of the base station and the UEaccording to the present embodiment;

FIG. 32 is a block diagram illustrating an internal structure of the UEaccording to an embodiment of the disclosure;

FIG. 33 is a block diagram illustrating an internal structure of thebase station according to an embodiment of the disclosure;

FIG. 34 illustrates an FD-MIMO system to which an embodiment of thedisclosure is applied;

FIG. 35 illustrates radio resources corresponding to one subframe andone RB which are minimum units that can be scheduled to the downlink inthe LTE and LTE-A systems;

FIG. 36 illustrates an example of CSI-RS RE mapping for n^(th) andn+1^(th) PRBs in the case in which the base station transmits CSI-RSs ofeight antenna ports;

FIG. 37 illustrates an example of BF CSI-RS operation;

FIG. 38 illustrates an example of CSI-RS transmission/reception and aCSI report according thereto;

FIG. 39 illustrates an example of a dynamic port numbering operationscenario for the aperiodic CSI-RS;

FIG. 40 illustrates another example of the dynamic port numberingoperation scenario for the aperiodic CSI-RS;

FIG. 41 illustrates an example of CSI-RS resource configurationinformation;

FIG. 42 illustrates another example of CSI-RS resource configurationinformation;

FIG. 43 illustrates an example of the second method for configuring andchanging the CSI-RS transmission band;

FIG. 44 illustrates a process in which the UE performs bandwidthadaptation through transmission band changing signaling;

FIG. 45 illustrates a process of controlling aperiodic CSI-RStransmission and reception bands through control channel CSI triggeringsignaling;

FIG. 46 illustrates a process of controlling aperiodic ZP CSI-RStransmission and reception bands;

FIG. 47 illustrates the operation of the base station for transmittingan aperiodic CSI-RS;

FIG. 48 illustrates the operation of the UE for receiving the aperiodicCSI-RS;

FIG. 49 is a block diagram illustrating an internal structure of the UEaccording to an embodiment of the disclosure; and

FIG. 50 is a block diagram illustrating an internal structure of thebase station according to an embodiment of the disclosure.

MODE FOR THE INVENTION

Hereinafter, embodiments of the disclosure will be described in detailwith reference to the accompanying drawings.

In describing the exemplary embodiments of the disclosure, descriptionsrelated to technical contents which are well-known in the art to whichthe disclosure pertains, and are not directly associated with thedisclosure, will be omitted. Such an omission of unnecessarydescriptions is intended to prevent obscuring of the main idea of thedisclosure and more clearly transfer the main idea.

For the same reason, in the accompanying drawings, some elements may beexaggerated, omitted, or schematically illustrated. Further, the size ofeach element does not entirely reflect the actual size. In the drawings,identical or corresponding elements are provided with identicalreference numerals.

The advantages and features of the disclosure and ways to achieve themwill be apparent by making reference to embodiments as described belowin detail in conjunction with the accompanying drawings. However, thedisclosure is not limited to the embodiments set forth below, but may beimplemented in various different forms. The following embodiments areprovided only to completely disclose the disclosure and inform thoseskilled in the art of the scope of the disclosure, and the disclosure isdefined only by the scope of the appended claims. Throughout thespecification, the same or like reference numerals designate the same orlike elements.

Here, it will be understood that each block of the flowchartillustrations, and combinations of blocks in the flowchartillustrations, can be implemented by computer program instructions.These computer program instructions can be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions specified in the flowchart block or blocks.These computer program instructions may also be stored in a computerusable or computer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer usable orcomputer-readable memory produce an article of manufacture includinginstruction means that implement the function specified in the flowchartblock or blocks. The computer program instructions may also be loadedonto a computer or other programmable data processing apparatus to causea series of operational steps to be performed on the computer or otherprogrammable apparatus to produce a computer implemented process suchthat the instructions that execute on the computer or other programmableapparatus provide steps for implementing the functions specified in theflowchart block or blocks.

And each block of the flowchart illustrations may represent a module,segment, or portion of code, which includes one or more executableinstructions for implementing the specified logical function(s). Itshould also be noted that in some alternative implementations, thefunctions noted in the blocks may occur out of the order. For example,two blocks shown in succession may in fact be executed substantiallyconcurrently or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved.

As used herein, the “unit” refers to a software element or a hardwareelement, such as a Field Programmable Gate Array (FPGA) or anApplication Specific Integrated Circuit (ASIC), which performs apredetermined function. However, the “unit does not always have ameaning limited to software or hardware. The “unit” may be constructedeither to be stored in an addressable storage medium or to execute oneor more processors. Therefore, the “unit” includes, for example,software elements, object-oriented software elements, class elements ortask elements, processes, functions, properties, procedures,sub-routines, segments of a program code, drivers, firmware,micro-codes, circuits, data, database, data structures, tables, arrays,and parameters. The elements and functions provided by the “unit” may beeither combined into a smaller number of elements, “unit” or dividedinto a larger number of elements, “unit”. Moreover, the elements and“units” may be implemented to reproduce one or more CPUs within a deviceor a security multimedia card. The disclosure may have variousmodifications and various embodiments, among which specific embodimentswill now be described more fully with reference to the accompanyingdrawings. However, it should be understood that there is no intent tolimit the disclosure to the particular forms disclosed, but on thecontrary, the disclosure is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the disclosure.

Further, it will be appreciated that singular expressions such as “an”and “the” include plural expressions as well, unless the context clearlyindicates otherwise. Accordingly, as an example, a “component surface”includes one or more component surfaces.

Although the terms including an ordinal number such as first, second,etc. can be used for describing various elements, the structuralelements are not restricted by the terms. The terms are used merely forthe purpose to distinguish an element from the other elements. Forexample, a first element could be termed a second element, andsimilarly, a second element could be also termed a first element withoutdeparting from the scope of the disclosure. As used herein, the term“and/or” includes any and all combinations of one or more associateditems.

The terms used herein are used only to describe particular embodiments,and are not intended to limit the disclosure. As used herein, thesingular forms are intended to include the plural forms as well, unlessthe context clearly indicates otherwise. In the disclosure, the termssuch as “include” and/or “have” may be construed to denote a certaincharacteristic, number, step, operation, constituent element, componentor a combination thereof, but may not be construed to exclude theexistence of or a possibility of addition of one or more othercharacteristics, numbers, steps, operations, constituent elements,components or combinations thereof.

Hereinafter, all the embodiments of the disclosure may not be exclusive,and one or more embodiments may be performed together. However, for easeof description, the embodiments and examples will be separatelydescribed.

First Embodiment

A wireless communication system has developed to be a broadband wirelesscommunication system that provides a high speed and high quality packetdata service, like the communication standards, for example, high speedpacket access (HSPA) of 3GPP, Long Term Evolution (LTE) or evolveduniversal terrestrial radio access (E-UTRA), LTE-advanced (LTE-A), highrate packet data (HRPD) of 3GPP2, ultra mobile broadband (UMB), and802.16e of IEEE, or the like, beyond the voice-based service provided atthe initial stage. 5G or new radio (NR) communication standard is beingresearched as the 5^(th) generation wireless communication system.

An LTE system, which is a representative example of the broadbandwireless communication system, employs an orthogonal frequency divisionmultiplexing (OFDM) scheme for a downlink (DL), and employs a singlecarrier frequency division multiple access (SC-FDMA) scheme for anuplink (UL). The uplink is a radio link through which a user equipment(UE) (or a mobile station (MS)) transmits data or a control signal to abase station (BS) (or an eNode B (eNB)), and the downlink is a radiolink through which the base station transmits data or a control signalto the UE. In such a multi-access scheme, time-frequency resources forcarrying data or control information are allocated and operated in amanner to prevent overlapping of resources, that is, to establishorthogonality, between users so as to identify data or controlinformation of each user. Hereinafter, the LTE system may include LTEand LTE-A systems.

When decoding fails at the initial transmission, the LTE system employshybrid automatic repeat request (HARQ) that retransmits thecorresponding data in a physical layer. In the HARQ scheme, when areceiver does not accurately decode data, the receiver transmitsinformation (negative acknowledgement: NACK) informing a transmitter ofa decoding failure and thus the transmitter may re-transmit thecorresponding data on the physical layer. The receiver combines the datare-transmitted by the transmitter with the data of which the previousdecoding failed, thereby increasing the data reception performance.Also, when the receiver accurately decodes data, the receiver transmitsinformation (acknowledgement: ACK) informing the transmitter of decodingsuccess, and thus the transmitter may transmit new data.

FIG. 1 illustrates the basic structure of a time/frequency region whichis a radio resource region in which the data or control channel istransmitted in downlink of the LTE system.

In FIG. 1, the horizontal axis indicates a time region and the verticalaxis indicates a frequency region. A minimum transmission unit in thetime region is an OFDM symbol. One slot 106 consists of OFDM symbols 102and one subframe 105 consists of 2 slots. The length of one slot is 0.5ms, and the length of one subframe is 1.0 ms. A radio frame 114 is atime region interval consisting of 10 subframes. A minimum transmissionunit in the frequency region is a subcarrier, and the bandwidth of anentire system transmission band consists of a total of N_(BW)subcarriers 104.

A basic unit of resources in the time-frequency region is a resourceelement (RE) 112 and may be indicated by an OFDM symbol index and asubcarrier index. A resource block (RB or physical resource block (PRB))108 is defined by N_(symb) successive OFDM symbols 102 in the timeregion and N_(RB) successive subcarriers 110 in the frequency region.Therefore, one RB 108 consists of N_(symb)×N_(RB) REs 112. In general, aminimum transmission unit of data is the RB unit. In the LTE system,generally, N_(symb)=7 and N_(RB)=12. N_(BW) is proportional to thebandwidth of the system transmission band. A data rate increases inproportion to the number of RBs scheduled in the UE.

The LTE system defines and operates 6 transmission bandwidths. In thecase of a frequency division duplex (FDD) system that operates byseparating a downlink and an uplink by frequency, a downlinktransmission bandwidth and an uplink transmission bandwidth may bedifferent from each other. A channel bandwidth may indicate an RFbandwidth corresponding to the system transmission bandwidth. [Table 1]indicates the relationship between a system transmission bandwidth and achannel bandwidth defined in the LTE system. For example, when the LTEsystem has a channel bandwidth of 10 MHz, the transmission bandwidth mayconsist of 50 RBs.

TABLE 1 Channel bandwidth 1.4 3 5 10 15 20 BWChannel [MHz] Transmissionbandwidth 6 15 25 50 75 100 confizuration NRB

Downlink control information is transmitted within first N OFDM symbolsin the subframe. Generally, N={1, 2, 3}. Accordingly, the N varies inevery subframe depending on an amount of control information whichshould be transmitted in the current subframe. The control informationincludes a control channel transmission interval indicator indicatinghow many OFDM symbols are used for transmitting the control information,scheduling information of downlink data or uplink data, and HARQACK/NACK signals.

In the LTE system, the scheduling information of downlink data or uplinkdata is transmitted from the base station to the UE through downlinkcontrol information (DCI). The DCI is defined in various formats. Thedetermined DCI format is applied and operated according to whether theDCI is scheduling information (UL grant) for uplink data or schedulinginformation (DL grant) for downlink data, whether the DCI is compact DCIhaving small size control information, whether the DCI applies spatialmultiplexing using multiple antennas, and whether the DCI is DCI forcontrolling power. For example, DCI format 1 corresponding to schedulingcontrol information on downlink data (DL grant) may be configured toinclude at least the following control information.

-   -   Resource allocation type 0/1, flag: notifies whether a resource        allocation type is type 0 or type 1. Type 0 applies a bitmap        scheme and allocates resources in units of resource block groups        (RBGs). In the LTE system, a basic scheduling unit is a resource        block (RB) expressed by time and frequency region resources, and        an RBG includes a plurality of RBs and is a basic scheduling        unit in the type 0 scheme. Type 1 allows allocation of a        predetermined RB in an RBG.    -   Resource block assignment: notifies of RBs allocated to data        transmission. Expressed resources are determined according to        the system bandwidth and the resource allocation type.

Modulation and coding scheme (MCS): indicates a modulation scheme usedfor data transmission and the size of a transport block (TB) which isdata to be transmitted.

-   -   HARQ process number: notifies of a process number of HARQ.    -   New data indicator: indicates whether data is transmitted by        HARQ initial transmission or retransmission.    -   Redundancy version: indicates a redundancy version of HARQ.    -   Transmit power control (TPC) command for physical uplink control        channel (PUCCH): indicates a transmission power control command        for a PUCCH which is an uplink control channel.

The DCI is transmitted through a physical downlink control channel(PDCCH) or enhanced PDCCH (EPDCCH) via a channel-coding and modulationprocess. Hereinafter, PDCCH or EPDCCH transmission may beinterchangeable with DCI transmission through the PDCCH or the EPDCCH.The description may be also applied to other channels.

In general, the DCI is scrambled with a particular radio networktemporary identifier (RNTI) (or a UE identifier), independently for eachUE, a cyclic redundancy check (CRC) bit is added thereto, and thenchannel coding is performed, whereby each independent PDCCH isconfigured and transmitted. In the time region, the PDCCH is mapped andtransmitted during the control channel transmission interval. Themapping location of the PDCCH in the frequency region is determined byan identifier (ID) of each UE and distributed to the entire systemtransmission band.

Downlink data is transmitted through a physical downlink shared channel(PDSCH) which is a physical channel for transmitting downlink data. APDSCH is transmitted after the control channel transmission interval.Scheduling information such as a modulation scheme, a specific mappinglocation in the frequency domain, or the like may be reported by DCItransmitted via a PDCCH.

Via an MCS formed of 5 bits in the control information included in theDCI, the base station may report the modulation scheme applied to aPDSCH to be transmitted to the UE and the size (transport block size(TBS)) of data to be transmitted. The TBS corresponds to the size beforechannel coding for error correction is applied to the data (TB) to betransmitted by the base station.

The modulation scheme supported by the LTE system includes quadraturephase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM),and 64QAM, and modulation orders (Qm) thereof correspond to 2, 4, and 6,respectively. That is, in the case of QPSK modulation, 2 bits may betransmitted per symbol. In the case of 16QAM modulation, 4 bits may betransmitted per symbol. In the case of 64QAM modulation, 6 bits may betransmitted per symbol.

FIG. 2 illustrates the basic structure of a time-frequency region whichis a radio resource region in which the data or control channel istransmitted in uplink of the LTE system according to the prior art.

Referring to FIG. 2, the horizontal axis indicates the time region andthe vertical axis indicates the frequency region. A minimum transmissionunit in the time region is an SC-FDM symbol 202 and one slot 206consists of N_(symb) SC-FDMA symbols. One subframe 205 consists of twoslots. A minimum transmission unit in the frequency region is asubcarrier and an entire system transmission band (transmissionbandwidth) 204 consists of a total of N_(BW) subcarriers. N_(BW) has avalue, which is proportional to the system transmission band.

A basic unit of resources in the time-frequency region is a resourceelement (RE) 212 and may be defined by an SC-FDMA symbol index and asubcarrier index. A resource block (RB) 208 is defined by N_(symb)successive SC-FDMA symbols in the time region and N_(BW) successivesubcarriers in the frequency region. Therefore, an RB consists ofN_(symb)×N_(RB) REs. In general, a minimum transmission unit of data orcontrol information is an RB. A PUCCH is mapped to a frequency regioncorresponding to 1 RB, and may be transmitted during one subframe.

The timing relation between a PDSCH which is a physical channel fortransmitting downlink data or a PDCCH or an EPDCCH includingsemi-persistent scheduling release (or SPS release) and a PUCCH or aPUSCH which is an uplink physical channel for transmitting HARQ ACK/NACKis defined in the LTE system. For example, in the LTE system operatingin FDD type, HARQ ACK/NACK corresponding to a PDSCH transmitted in ann−4^(th) subframe or a PDCCH or an EPDCCH including SRS release istransmitted through a PUCCH or a PUSCH in an n^(th) subframe.

In the LTE system, downlink HARQ adapts an asynchronous HARQ scheme inwhich a data retransmission time is not fixed. That is, when the basestation receives a feedback of HARQ NACK from the UE with respect toinitial transmission data that the base station transmitted, the basestation freely determines the time point at which the data isretransmitted via a scheduling operation. For the HARQ operation, the UEbuffers data which is determined to be an error as a result of decodingreceived data, and combines the data with subsequently retransmitteddata.

When the UE receives a PDSCH including downlink data transmitted fromthe base station through subframe n, the UE transmits uplink controlinformation including HARQ ACK or NACK of the downlink data to the basestation through a PUCCH or a PUSCH in subframe n k. In this instance, kis defined differently according to FDD or time division duplex (TDD) ofthe LTE system and a configuration of the subframe. For example, in thecase of the FDD LTE system, k is fixed to 4. Meanwhile, in the case ofthe TDD LTE system, k may be changed according to a subframeconfiguration and a subframe number.

In the LTE system, uplink HARQ adapts a synchronous HARQ scheme in whichthe data transmission time point is fixed unlike downlink HARQ. That is,the uplink/downlink timing relation between a physical uplink sharedchannel (PUSCH) which is a physical channel for uplink datatransmission, and a PDCCH which is a downlink control channel aheadthereof and a physical hybrid indicator channel (PHICH) which is aphysical channel for transmitting downlink HARQ ACK/NACK correspondingto uplink data on the PUSCH is fixed by the following rule.

When the UE receives a PDCCH including uplink scheduling controlinformation transmitted from the base station or a PHICH fortransmitting downlink HARQ ACK/NACK through subframe n, the UE transmitsuplink data corresponding to the control information through a PUSCH insubframe n+k. At this time, k is differently defined depending on FDD orTDD of the LTE system and the configuration thereof. For example, in thecase of the FDD LTE system, k is fixed to 4. In the case of the TDD LTEsystem, k may be changed according to a subframe configuration and asubframe number.

Further, when the UE receives a PHICH for transmitting downlink HARQACK/NACK from the base station in sub-frame i, the PHICH corresponds toa PUSCH which the UE transmits in subframe i-k. In this instance, k isdefined differently depending on FDD or TDD of the LTE system, and aconfiguration thereof. For example, in the case of the FDD LTE system, kis fixed to 4. Meanwhile, in the case of the TDD LTE system, k may bechanged according to a subframe configuration and a subframe number.

The description of the wireless communication system has been made onthe basis of the LTE system, but the disclosure is not limited to theLTE system and may be applied to various wireless communication systemssuch as NR and 5G.

FIGS. 3 and 4 illustrate examples in which data for enhanced MobileBroadBand (eMBB), ultra-reliable and low latency communications (URLLC),and massive machine type communication (mMTC) which are servicesconsidered in the 5G or NR system are allocated to frequency-timeresources.

In FIG. 3, eMBB, URLLC, and mMTC data are allocated to an entire systemfrequency band 300. When URLLC data 303, 305, and 307 are generatedwhile eMBB data 301 and mMTC data 309 are allocated to a specificfrequency band and transmitted, and thus transmission thereof is needed,the transmitter may empty parts to which the eMBB data 301 and the mMTCdata 309 have been already allocated and transmit the URLLC data 303,305, and 307. Particularly, a short delay time is important to the URLLCamong the services, so that the URLLC data 303, 305, and 307 may betransmitted while being allocated to parts of the resources 301 to whichthe eMBB is allocated. Of course, when the URLLC is additionallyallocated and transmitted in resources to which the eMBB is allocated,eMBB data may not be transmitted in duplicate frequency-time resourcesand accordingly the performance of eMBB data transmission may bereduced. That is, in the above case, eMBB data transmission may befailed due to URLLC allocation.

In FIG. 4, an entire system frequency band 400 may be divided intosubbands 402, 404, and 406 and used for transmitting services and data.The subbands may be divided in advance and information thereof may betransmitted to the UE through higher signaling or the base station mayrandomly divide the subbands and provide services to the UE without anyinformation on the subbands. FIG. 4 illustrates an example in which asubband 402 is used for eMBB data transmission 408, a subband 404 isused for URLLC data transmission 410, 412, and 414, and a subband 406 isused for mMTC data transmission 416. In FIGS. 3 and 4, the length of atransmission time interval (TTI) used for URLLC transmission may beshorter than the length of a TTI used for eMBB or mMTC transmission.

Hereinafter, an embodiment of the disclosure will be described in detailwith reference to the accompanying drawings. In the followingdescription of the disclosure, a detailed description of known functionsor configurations incorporated herein will be omitted when it may makethe subject matter of the disclosure rather unclear. The terms whichwill be described below are terms defined in consideration of thefunctions in the disclosure, and may be different according to users,intentions of the users, or customs. Therefore, the definitions of theterms should be made based on the contents throughout the specification.

Hereinafter, the base station is the entity that allocates resources tothe UE, and may be at least one of an eNode B, a Node B, a base station(BS), a radio access unit, an base station controller, and a node on anetwork. The UE may include a user equipment (UE), a mobile station(MS), a cellular phone, a smartphone, a computer, and a multimediasystem capable of performing a communication function. Hereinafter, theembodiment of the disclosure is described on the basis of the LTE orLTE-A system by way of an example, but the embodiment of the disclosuremay be applied to other communication systems having a similar technicalbackground or channel form. For example, 5 generation mobilecommunication technology (5G, new radio (NR)) developed after LTE-A maybe included therein. Also, the embodiment of the disclosure may bemodified without departing from the scope of the disclosure, and may beapplied to other communication systems by the determination by thoseskilled in the art.

Particularly, terms “physical channel” and “signal” in the conventionalLTE or LTE-A system may be used to describe the method and the apparatusproposed by the disclosure. However, embodiments of the disclosure canbe applied to a wireless communication system rather than the LTE andLTE-A systems.

Further, the embodiment of the disclosure can be applied to FDD and TDDsystems.

Hereinafter, in the disclosure, physical layer signaling is a method oftransmitting a signal from the base station to the UE through a downlinkcontrol channel of a physical layer or from the UE to the base stationthrough an uplink control channel of a physical layer and may bereferred to as L1 signaling or PHY signaling.

In the disclosure, higher signaling or higher layer signaling is amethod of transmitting a signal from the base station to the UE througha downlink data channel of a physical layer or from the UE to the basestation through an uplink data channel of a physical layer and may bereferred to as RRC signaling, L2 signaling, PDCP signaling, or a MACcontrol element (MAC CE).

In the disclosure, a TPMI indicates a transmit precoding matrixindicator or transmit precoding matrix information and, similarly, maybe expressed as beamforming vector information or beam directioninformation

In the disclosure, uplink (UL) DCI or UL-related DCI is physical layercontrol signaling (L1 control) including information required for uplinktransmission such as uplink resource configuration information andresource configuration type information like UL grant, uplink powercontrol information, cyclic shift of an uplink reference signal, anorthogonal cover code (OCC), a channel state information (CSI) request,a sounding reference signal (SRS) request, MCS information for eachcodeword, and an uplink precoding information field.

In the wireless communication system such as LTE and LTE-A, discreteFourier transform spread orthogonal frequency division multiplexing(DFT-S OFDM) is used to reduce PAPR and improve coverage in uplinktransmission. Further, the LTE and LTE-A systems consider only a smallnumber of UE transmission antennas according to a supported bandcharacteristic and a hardware development step. Accordingly,diversity-based transmission is not supported in consideration of thecharacteristic.

However, unlike the current wireless communication system assuming amaximum of four UE transmission antennas, it is highly likely to usefour or more transmission antennas by the UE due to improvement of anantenna form factor and development of RF technology through ahigh-frequency carrier in the NR system. Conventional DFT-S OFDM is usedonly for transmission of rank 1 and transmission using CP-OFMD issupported in transmission of rank 2 or higher. Accordingly, in the NRwireless communication system, demands of diversity transmission inuplink increase. Therefore, the disclosure proposes a method oftransmitting a signal in uplink through a diversity scheme and a methodof indicating a diversity scheme.

Hereinafter, it is assumed that dynamic beamforming or semi-dynamicbeamforming is supported to perform uplink transmission in variousscenarios in the disclosure.

FIG. 5 illustrates an example of uplink transmission through dynamicbeamforming or semi-dynamic beamforming.

Dynamic beamforming is suitable for the case in which a movement speedof the UE is low, separation between cells is good, or accurate uplinkchannel information is available like in a situation in which inter-cellinterference management is good. In this case, a UE 702 may performuplink transmission using a beam having a narrow beam width on the basisof accurate uplink channel direction information. A base station 701notifies the UE of a TPMI through UL DCI such as UL grant. Afterreceiving TPMI signaling, the UE transmits uplink data to the basestation through a precoder indicated by the TPMI or a beamforming vector(or matrix).

Multi-input multi-output (MIMO) transmission based on a codebook forsupporting the dynamic beamforming may be operated by UL DCI including aprecoding information (precoding matrix indicator (PMI)) field(determined according to a rank indicator (RI) when the corresponding RIexists). At this time, the precoding information field indicates aprecoding matrix used for uplink transmission allocated to thecorresponding UE. The precoding matrix may be appointed to direct onedirection in the allocated entire band in the case of wideband precodinginformation and to direct one direction for each subband in the case ofsubband precoding information. At this time, a precoding vectordesignated by the subband precoding information may be included in aprecoding vector group designated by the wideband precoding information.Accordingly, signaling burden for subband precoding information may bereduced.

The semi-dynamic beamforming is suitable for the case in which amovement speed of the UE is high, separation between cells is not good,or uplink channel information is inaccurate like in the situation inwhich inter-cell interference management is not good. In this case, theUE 703 may perform uplink transmission using a beam group includingbeams in various directions on the basis of schematic uplink channeldirection information. The base station 701 notifies the UE of a TPMIthrough UL DCI such as UL grant. After receiving TPMI signaling, the UEtransmits uplink data to the base station through a subset of theprecoder indicated by the TPMI or a subset of the beamforming vector (ormatrix).

MIMO transmission based on a codebook for supporting the semi-dynamicbeamforming may be operated by UL DCI including a precoding information(PMI) field (determined according to an RI when the corresponding RIexists). At this time, the precoding information field indicates a groupof a precoding vector used for uplink transmission allocated to thecorresponding UE. Information on the group of the precoding vector iswideband information and may be equally used in the entire uplink band.The UE can apply precoder cycling according to a predetermined patternto beams included in the notified precoding vector group, and theprecoder cycling may be supported through diversity-based transmissionto the UE.

FIG. 6 illustrates an example in which the UE and the base stationtransmit a reference signal in order to acquire channel stateinformation required for uplink transmission in the NR system.

Transmission of a reference signal supported by the NR system may use aCSI-RS beam in units of cells which is a wide area for supporting aplurality of antennas or in units of sectors and may vary depending onwhether a non-precoded CSI-RS (NP CSI-RS) 610 is used to performbeamforming using precoding feedback of the UE or a beamformed CSI-RS(BF CSI-RS) 630 is used to reduce CSI-RS overhead by applyingbeamforming to antennas In the case of the corresponding NP CSI-RS, aplurality of unit resource configurations may be used to support manyantenna ports, and in the case of the BF CSI-RS, a plurality of CSI-RSsources may be configured rather than the unit resource configurationsand the UE may select one or a plurality of resources therefrom andreport channel state information.

Similarly, when the UE transmits the SRS, an NP SRS 620 supporting manyantennas in one SRS resource and a BF SRS 640 using information on oneor a plurality of SRS resources configured in the UE may be applied. Thebase station may transmit the SRS through the SRS resources configuredby the base station, receive the corresponding SRS, indicate an optimaltransmission beam required between the UE and the base station to theUE, and discover a reception beam optimized for the base station.Further, if channel reciprocity or beam determination match betweenuplink and downlink, an uplink beam may be selected using the NP CSI-RS610 and the BF CSI-RS 630.

A precoding vector group or a beam group in uplink can be definedthrough two methods below.

A first method is a method of defining a beam group on the basis of ahierarchical PMI. For example, the PMI indicating one code point mayinclude two or more sub PMIs. If it is assumed that the PMI consists oftwo sub PMIs, it may be appointed that a first PMI is one of beam groupindexes including a specific number of precoding vectors and a secondPMI is one of indexes of precoding vectors included in the beam group.For example, an uplink codebook including beam groups G_(i) including MUE transmission antennas and B DFT precoding vectors v_(k) based on anoversampling factor of 0 may be defined as [Equation 1] below.

$\begin{matrix}{\mspace{76mu}{{v_{k} = {\frac{1}{\sqrt{M}} \times \left\lbrack {1\mspace{14mu} e^{j\frac{2\pi\; k}{OM}}\mspace{14mu} e^{j\frac{4\pi\; k}{OM}}\mspace{14mu}\cdots\mspace{14mu} e^{j\frac{2{\pi{({M - 1})}}k}{OM}}} \right\rbrack^{T}}}{G_{i} = \left\lbrack {v_{Ai}\mspace{14mu} v_{{mod}{({{{Ai} + 1},{OM}})}}\mspace{14mu}\cdots\mspace{14mu} v_{{mod}{({{{Ai} + B - 2},{OM}})}}\mspace{14mu} v_{{mod}{({{{Ai} + B - 1},{OM}})}}} \right\rbrack}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

A is a beam skipping factor and denotes an interval (beam unit) betweenbeam groups. In this example, a first PMI i is an index of the beamgroup, and a single precoding vector can be designated by a second PMIhaving payload of ┌log₂B┐.

A second method is a method of defining a beam or a beam group on thebasis of a single-structure PMI. For example, one PMI may be understoodas an indicator indicating a single beam or beam group according tohigher layer or physical layer signaling. For example, an uplinkcodebook including beam groups G_(i) including M UE transmissionantennas, i^(th) DFT precoding vector v_(i) based on an oversamplingfactor of 0, and B DFT precoding vectors may be defined as [Equation 2]below.

$\begin{matrix}{{v_{k} = {\frac{1}{\sqrt{M}} \times \left\lbrack {1\mspace{14mu} e^{j\frac{2\pi\; k}{OM}}\mspace{14mu} e^{j\frac{4\pi\; k}{OM}}\mspace{14mu}\cdots\mspace{14mu} e^{j\frac{2{\pi{({M - 1})}}k}{OM}}} \right\rbrack^{T}}}{G_{i} = {\quad\left\lbrack {v_{i}\mspace{14mu} v_{{mod}{({{i + 1},{OM}})}}\mspace{14mu}\cdots\mspace{14mu} v_{{mod}{({{i + B - 2},{OM}})}}\mspace{14mu} v_{{mod}{({{i + B - 1},{OM}})}}} \right\rbrack}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

In this example, an i^(th) PMI may be understood to indicate v_(i) whenthe high layer or physical layer signaling indicates dynamic beamformingor wideband precoding. On the other hand, the i^(th) PMI may beunderstood to indicate G_(i) when the higher layer or physical layersignaling indicates semi-dynamic beamforming or subband precoding.[Table 2] shows an example of a TPMI analysis method when dynamic orsemi-dynamic beamforming transmission or wideband or subband precodingis designated by higher layer signaling in the example. [Table 3] showsan example of a TPMI analysis method when dynamic or semi-dynamicbeamforming transmission or wideband or subband precoding is designatedby physical layer signaling in the example.

TABLE 2 Precoder or precoder group PMI BeamformingScheme =BeamformingScheme = value i ‘Dynamic’ ‘Semi-dynamic’ 0 V₀ G₀ 1 v₁ G₁ 2v₂ G₂ . . . . . . . . . OM − 1 V_(OM−1) G_(OM−1)

TABLE 3 Interpretation PMI value i Beamforming scheme Precoder orprecoder group 0 Dynamic Precoder v₀ 1 Dynamic Precoder v₁ 2 DynamicPrecoder v₂ . . . . . . . . . OM − 1 Dynamic Precoder v_(0M−1) OMSemi-dvnamic Precoder group G₀ OM + 1 Semi-dynamic Precodergroup G₁ OM +2 Semi-dynamic Precoder group G₂ . . . . . . . . . 2OM − 1 Semi-dynamicPrecoder group G_()OM−1)

In [Equation 1] and [Equation 2], it is assumed that UE transmissionantennas have a one-dimensional antenna array and thus the codebookincludes one-dimensional DFT vectors, but another type of an uplinkcodebook may be used if the UE transmission antennas have atwo-dimensional antenna array. For example, if the UE transmissionantenna array includes M₁ antenna ports in a first dimension and M₂antenna ports in a second dimension, a precoding vector v m₁,m₂ andabeam group G m₁,m₂ may be defined as shown in [Equation 3] through apair of indexes (m₁, m₂).

$\begin{matrix}{{v_{m_{1},m_{2}} = {{\frac{1}{\sqrt{M_{1}M_{2}}} \times {\left\lbrack {1\mspace{14mu} e^{\frac{2\pi\; m_{1}}{O_{1}M_{1}}}\mspace{14mu} e^{j\frac{4\pi\; m_{1}}{O_{1}M_{1}}}\mspace{14mu}\cdots\mspace{14mu} e^{j\frac{2{\pi{({M_{1} - 1})}}m_{1}}{O_{1}m_{1}}}} \right\rbrack^{T} \otimes \left\lbrack {1\mspace{14mu} e^{\frac{2\pi\; m_{2}}{O_{2}M_{2}}}\mspace{14mu} e^{j\frac{4\pi\; m_{2}}{O_{2}M_{2}}}\mspace{14mu}\cdots\mspace{14mu} e^{j\frac{2{\pi{({M_{2} - 1})}}m_{2}}{O_{2}M_{2}}}} \right\rbrack^{T}}} = {v_{m_{1}} \otimes v_{m_{2}}}}}\mspace{76mu}{G_{m_{1},m_{2}} = {G_{m_{1}} \otimes G_{m_{2}}}}{G_{m_{i}} = \left\lbrack {v_{m_{i}}\mspace{14mu} v_{{mod}{({{m_{i} + 1},{O_{i}M_{i}}})}}\mspace{14mu}\cdots\mspace{14mu} v_{{mod}{({{m_{i} + B_{i} - 2},{O_{i}M_{i}}})}}\mspace{14mu} v_{{mod}{({{m_{i} + B_{i} - 1},{O_{i}M_{i}}})}}} \right\rbrack}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

It is assumed that UE transmission antennas have the same polarizationin [Equation 1], [Equation 2], and [Equation 3], but if the UEtransmission antennas have a dual-polarized array, examples of theuplink codebook can be changed in consideration thereof. For example, ifthe UE transmission antennas have a one-dimensional array including Mantenna ports for each polarization, that is, a total of 2M antennaports, a rank 1 precoding vector v_(i,k) and a beam group G_(m) can bedefined as shown in [Equation 4] below.

$\begin{matrix}{\mspace{76mu}{{{v_{i,k} = {\frac{1}{\sqrt{2M}} \times \begin{bmatrix}d_{i} \\{\Phi_{k}d_{i}}\end{bmatrix}}}\mspace{76mu}{{d_{i} = \left\lbrack {1\mspace{14mu} e^{j\frac{2\pi\; i}{OM}}\mspace{14mu} e^{j\frac{4\pi\; i}{OM}}\mspace{14mu}\cdots\mspace{14mu} e^{j\frac{2{\pi{({M - 1})}}i}{OM}}} \right\rbrack^{T}},{\Phi_{k} = e^{\frac{j\; 2\pi\; k}{K}}}}{G_{m} = \left\lbrack {v_{m}\mspace{14mu} v_{{mod}{({{m + 1},{OM}})}}\mspace{14mu}\cdots\mspace{14mu} v_{{mod}{({{m + B - 2},{OM}})}}\mspace{14mu} v_{{mod}{({{m + B - 1},{OM}})}}} \right\rbrack}},{m = {{\left( {K - 1} \right)i} + k}}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack\end{matrix}$

In [Equation 4], K denotes a co-phasing quantization level.

In another example, if the UE transmission antennas have atwo-dimensional array including M₁M₂ antenna ports for eachpolarization, that is a total of 2M₁M₂ antenna ports, a rank 1 precodingvector v m₁,m₂,k can be defined as shown in [Equation 5] below. M₁ andM₂ are numbers of UE transmission antenna ports for each polarizationincluded in the first dimension and the second dimension. In the case ofthe beam group, the configuration similar to [Equation 3] can be made onthe basis of V m₁,m₂,k of [Equation 5].

$\begin{matrix}{{v_{m_{1},m_{2},k} = {\frac{1}{\sqrt{2M_{1}M_{2}}} \times \begin{bmatrix}{d_{m_{1}} \otimes d_{m_{2}}} \\{e^{\phi_{k}}{d_{m_{1}} \otimes d_{m_{2}}}}\end{bmatrix}}}{d_{m_{1}} = \left\lbrack {1\mspace{14mu} e^{j\frac{2\pi\; m_{1}}{O_{1}M_{1}}}\mspace{14mu} e^{j\frac{4\pi\; m_{1}}{O_{1}M_{1}}}\mspace{14mu}\cdots\mspace{14mu} e^{j\frac{2{\pi{({M_{1} - 1})}}m_{1}}{O_{1}M_{1}}}} \right\rbrack^{T}}{d_{m_{2}} = \left\lbrack {1\mspace{14mu} e^{j\frac{2\pi\; m_{2}}{O_{2}M_{2}}}\mspace{14mu} e^{j\frac{4\pi\; m_{2}}{O_{2}M_{2}}\mspace{14mu}\cdots}\mspace{14mu} e^{j\frac{2{\pi{({M_{2} - 1})}}m_{2}}{O_{2}M_{2}}}} \right\rbrack^{T}}} & \left\lbrack {{Equation}\mspace{14mu} 5} \right\rbrack\end{matrix}$

It is apparent that the dynamic/semi-dynamic beamforming orwideband/subband preceding signaling example, that is [Table 2] and[Table 3] can be easily applied to the codebook examples.

The examples have been described on the basis of the rank 1 codebookindicating a single direction, but this principle is not limited theretoin real implementation and can be equally applied to codebooks of rank 2or higher directing two or more directions.

The examples assume the case in which UL DCI includes one TPMI, and theUE receiving the TPMI can apply uplink precoding for one beam directionor one beam group to the entire uplink band.

FIG. 7 illustrates an example of allocating resources for uplinktransmission and applying subband precoding. For example, the basestation may transmit N_(PMI) TPMIs including precoding information for aplurality of subbands, for example, N_(PMI) subbands through UL DCI forsubband precoding. The value of N_(PMI) is determined by the numberRA_(RB) of uplink resources (RBs) allocated to the UE, the numberP_(SUBBAND) of RBs included in the subband, and an uplink resourceallocation method.

Reference numeral 710 indicates uplink resources when contiguous RBs areallocated and reference numeral 720 indicates uplink resources whenclustered RBs are allocated. In FIG. 7, the case in which P_(SUBBAND)=4is assumed. If resources are allocated as indicated by reference numeral710, that is, if resources configured as one cluster are allocated, thenumber of necessary subbands can be calculated through [Equation 6]based on RA_(R)B and P_(SUBBAND). The cluster is a set of contiguouslyallocated uplink RBs.

$\begin{matrix}{N_{PMI} = {\left\lceil \frac{{RA}_{RB}}{P_{SUBBAND}} \right\rceil.}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

However, if resources configured as one or more clusters are allocatedas indicated by reference numeral 720, calculation of [Equation 6] maynot be accurate in which case N_(PMI) can be calculated on the basis ofa method of [Equation 7] or [Equation 8]. [Equation 7] is a method forcalculating N_(PMI) on the basis of the lowest index RB_(low) and thehighest index RB_(high) among the allocated RBs. [Equation 8] is amethod for calculating N_(PMI) on the basis of the number of contiguousRBs allocated for each cluster. In [Equation 8], RA_(RB,n) denotes thenumber of contiguous RBs allocated to an n^(th) cluster and N denotesthe number of clusters allocated to the UE.

$\begin{matrix}{N_{PMI} = \left\lceil \frac{{RB}_{high} - {RB}_{low} + 1}{P_{SUBBAND}} \right\rceil} & \left\lbrack {{Equation}\mspace{14mu} 7} \right\rbrack \\{N_{PMI} = {\left\lceil \frac{{RA}_{{RB},1}}{P_{SUBBAND}} \right\rceil + \cdots + \left\lceil \frac{{RA}_{{RB},N}}{P_{SUBBAND}} \right\rceil}} & \left\lbrack {{Equation}\mspace{14mu} 8} \right\rbrack\end{matrix}$

If one uplink PMI includes T bits, transmission of TPMI payload ofN_(PMI)T bits may be needed for uplink subband preceding in the example.This means that scores of bits or more may be needed for TPMI signalingwhen several subbands and a codebook of several bits are used. It may betoo burdensome to transmit UL DCI and thus definition of a new method ofperforming UL subband precoding may be needed to reduce the UL DCIburden. If an environment supporting subband precoding is defined inuplink transmission, UL DCI coverage of the UE having a small number oftransmission and reception antennas may be improved, and uplinktransmission performance and total system performance of the UE may beimproved by supporting subband preceding of the UE having a large numberof transmission and reception antennas.

Embodiment 1-1

The UE may transmit uplink signals by applying different precodingsusing a plurality of demodulation reference signals (DMRSs) for each REon the frequency axis in order to perform uplink diversity-basedtransmission. FIG. 8 illustrates a method of applying differentprecodings to REs proposed by the present embodiment on the assumptionthat two DMRS ports are used.

In FIG. 8, the UE may apply different precodings to REs through two DMRSports within one RB. At this time, the base station may allocate andindicate a plurality of DMRSs for the transmission to the UE, and the UEreceiving the same may transmit data through the plurality of DMRSports. The method may provide a larger number of diversity gains evenwhen resources are allocated to the UE in a small number RBs, andadditional diversity gains may be expected by adding and using precodercycling at a physical resource block (PRB) or preceding resource blockgroup (PRO) level.

Since RE level precoder cycling uses different precoders according tofrequencies, it may not be used for uplink data transmission usingDiscrete Fourier Transform-spread-OFDM (DFT-S OFDM) and is efficient inthe case of cyclic prefix OFDM (CP-OFDM). In addition, in order toincrease the diversity gain, different precoders may be applied tosymbols as illustrated in FIG. 9.

FIG. 9 illustrates an example in which RE-specific mapping ofapplication of a precoder to each symbol is different to increase adiversity gain. FIG. 10 illustrates a comparison between performance1010 of the precoder cycling method illustrated in FIG. 8 andperformance 1020 of the precoder cycling method illustrated in FIG. 9.As illustrated in FIG. 10, in the method of FIG. 9, the UE should applymore complex precoder mapping but may have better results in terms ofperformance than the method of FIG. 8.

Embodiment 1-2

The UE may transmit uplink signals by applying different precodingsusing a plurality of DMRS ports for each time unit resource in order toperform uplink diversity-based transmission. FIGS. 11A and 11Billustrate an example in which different precodings are applied to timeresource units proposed by the present embodiment on the assumption thatthe number of DMRS ports which is the same as the number of transmittedranks.

It is assumed that the UE circulates the precoder for each slot ormini-slot as indicated by reference numerals 1110 and 1120. For example,as indicated by reference numeral 1110, a first slot is transmittedusing DMRS port 0 and a second slot is transmitted using DMRS port 1.This is a method of supporting diversity transmission based on precodercycling using the DRMS port transmitted for each slot or mini-slot onthe basis of the DMRS structure in which some REs of one symbol are usedfor one DMRS port.

The precoder cycling method has an advantage in that diversitytransmission can be supported for the UE without any increase inoverhead of the DMRS port. The UE may estimate a channel of thecorresponding unit resource through a channel of the DMRS port of theunit resource allocated for the corresponding precoder.

As indicated by reference numerals 1130 and 1140, a method ofcirculating two or four precoders for each OFDM symbol on the basis ofthe DRMS structure in which some REs of one symbol are used for one DMRSport is illustrated. The method indicated by reference numerals 1130 and1140 may have a shorter precoder cycling unit and thus may obtain higherdiversity than the method indicated by reference numerals 1110 or 1120.

Embodiment 1-3

FIG. 12 illustrates an example of precoder cycling in units of timebased on the assumption that DMRSs are transmitted in one entire symbol.

In FIG. 12, it is assumed that Zadoff-Chu sequence is used for the DMRS,but various sequences such as pseudo noise (PN), gold sequence, or CDMmay be supported. A ZC-based non-orthogonal DMRS multiplexing method maysupport a relatively larger number of DMRS ports within one symbol.Accordingly, as indicated by reference numeral 1210, differentprecodings for each OFDM symbol may be applied using a plurality of DMRSports within one RB. Examples in which different precodings are appliedto OFDM symbols using a plurality of DMRS ports are indicated byreference numerals 1220 and 1230. At this time, the base station mayallocate and indicate a plurality of DMRSs for the transmission to theUE, and the UE receiving the same may transmit data through theplurality of DMRS ports. The method may provide larger diversity gainsthrough time unit precoding cycling even when resources are allocated tothe UE in a smaller number of RBs, and additional diversity gains may beexpected by adding and using precoder cycling at the PRB or PRG level.Further, the method uses the same precoder in the time unit and thus canbe applied to uplink data transmission using DFT-S OFDM.

Embodiment 1-4

The UE may transmit uplink signals by applying different precodingsusing a plurality of DMRS ports for each RB or PRG in order to performuplink diversity-based transmission. FIG. 13 illustrates an example inwhich different precodings are applied to RBs or PRGs proposed by thepresent embodiment based on the assumption that two DMRS ports are used.

In FIG. 13, the UE may apply different precodings to REs through thenumber of DMRS ports which is the same as the number of rankstransmitted for each RB or PRG by the UE. At this time, the base stationmay allocate and indicate DMRSs for the transmission to the UE, and theUE receiving the same may transmit data through the DMRS ports. Sincethe precoder cycling at the RB or PRG level uses different precoders foreach frequency, the precoder cycling may not be used for uplink datatransmission using DFT-S OFDM and is efficient in the case of CP-OFDM isused.

Embodiment 1-5

The base station may transmit the following information to the UE foruplink transmission.

-   -   Carrier indicator—indicates which carrier is used for        corresponding uplink transmission.    -   Frequency hopping indicator—indicates whether frequency hopping        is performed.    -   RB allocation and hopping resource allocation—allocates RBs and        hopping resources to be used for uplink transmission by the UE.        Analysis of the field may vary depending on whether the UE        receives information indicating that hopping is performed from        the hopping indicator.    -   MCS and RV—indicates RV required for demodulation, channel        coding, and HRQ operation to be used for uplink transmission by        the UE.    -   New data indicator—indicates whether corresponding data is new        data.    -   DMRS indicator—indicates a DMRS port required for corresponding        data transmission. If OCC-based orthogonal multiplexing is        supported, necessary OCC information may also be transmitted,        and in the case of ZC sequence-based transmission, cyclic shift        information required for the ZC sequence may also be        transmitted.    -   CSI request indicator—triggered when aperiodic channel state        information is needed    -   SRS request indicator—triggered when aperiodic SRS transmission        is needed.    -   Resource allocation type—indicate resource allocation type        required for uplink transmission.    -   Transmitted rank indicator (TRI)—indicates rank information        required for uplink transmission.    -   Transmitted precoding matrix indicator (TPMI)—indicates PMI        information required for uplink transmission. At this time, only        the wideband TPMI can be transmitted in order to reduce DCI        overhead, and if possible, both the wideband TPMI and the        subband TPMI can be transmitted.

The base station may indicate diversity transmission to the UE on thebasis of the information, and when the UE receives the indication, theUE may receive indication of diversity transmission from the basestation through TRI information. For example, precoder cycling isapplied to a specific rank, and if another rank is indicated, precodercycling is not applied. [Table 4] shows such an embodiment.

TABLE 4 Example 1 RI = 1 rank1 transmission with non-diversitytransmission RI > 1, rank 1 transmission with diversity transmissionwith RI precoders Example 2 RI = 1, rank1 transmission withnon-diversity transmission RI = 2, rank2 transmission with non-diversitytransmission RI > 1, rank 1 transmission with diversity transmissionwith n precoders

If the base station indicates rank 1 transmission to the UE as shown inexample 1 of FIG. 4, the UE may not support precoder cycling nordiversity-based transmission. If transmission of rank 2 or higher isindicated, the UE applies precoder cycling or diversity-basedtransmission. As shown in example 2, the UE does not supportdiversity-based transmission in transmission of rank 2 or lower. Onlywhen transmission of rank 3 or higher is indicated, the UE can applyprecoder cycling or diversity-based transmission or differenttransmission may be applied to other ranks other than ranks 2 and 3.Accordingly, the base station may indicate diversity-based transmissionwithout any additional DCI bit or DCI format for diversity-basedtransmission.

At this time, the existing codebook may be used for the diversity-basedtransmission. FIG. 14A illustrates an example of using the codebook forthe diversity-based transmission.

In FIG. 14A, it is assumed that the UE receives allocation of a TRI of 3and a TPMI of 0 and precoder cycling for each RB mentioned in embodiment1-4 is applied.

At this time, precoding indicated by TPMI may be applied to a cyclingunit used for cycling. That is, a precoder 1400 for layer 0 may beapplied to RB #0, a precoder 1410 for layer 1 may be applied to RB #1,and a precoder 1420 for layer 2 may be applied to RB #2. It has beendescribed only based on <embodiment 1-4>, the description can be appliedto all of <embodiment 1-1> to <embodiment 1-4> and other diversity-basedtransmission methods.

The TRI may be indicated separately from the TPMI but indicated togetherwith the TPMI. [Table 6] shows a method of indicating the TRI and theTPMI together.

TABLE 6 One codeword: Two codewords: Codeword 0 enabled Codeword 0enabled Codeword 1 disabled Codeword 1 enabled Bit field mapped Bitfield mapped to index Message to index Message  0 1 layer:  0 2 layers:TPMI = 0 TPMI = 0  1 1 layer:  1 2 layers: TPMI = 1 TPMI = 1 . . . . . .. . . . . . 23 1 layer: 15 2 layers: TPMI = 23 TPMI = 15 24 2 layers: 163 layers: TPMI = 0 TPMI = 0 25 2 layers: 17 3 layers: TPMI = 1 TPMI = 1. . . . . . . . . . . . 39 2 layers: 27 3 layers: TPMI = 15 TPMI = 1140-63 reserved 28 4 layers: TPMI = 0 29-63 Reserved

In this case, a field for the indication may be referred to as anindicator of precoding information and the number of layers.

A configuration indicating whether to use the method may be indicatedusing RRC or a DCI field. If the RRC is not configured, it is consideredas non-diversity transmission and thus all layers may be transmittedtogether in the same resource. If RRC is configured, the layer maycirculated for each resource as described above. In the case of theindication using the DCI field, corresponding TRI and TPMI informationare transmitted on the basis of transmission other than diversitytransmission when DCI is 0 and the corresponding TRI and TPMIinformation are transmitted on the basis of diversity transmission whenDCI is 1. At this time, a rank used for diversity transmission may befixed to a lower rank which is different from the actually indicatedrank, for example, to rank 1 or rank 2. To this end, support usinganother table is possible.

The embodiment has an advantage in that the number of precoders requiredfor precoder cycling can be dynamically controlled. For example, if rank3 transmission and rank 4 transmission are configured and all of thetransmissions can use rank 1 transmission based on diversity, the basestation may indicate rank 3 when three precoder cycling-basedtransmission is desired and indicate rank 4 when four precodercycling-based transmission is desired, and the UE may decode downlinkdata on the basis of precoder cycling based on the indication of thebase station.

In addition, each rank indication may also support diversity-basedtransmission of other ranks. For example, rank 3 may supportdiversity-based transmission of rank 1 and rank 4 may supportdiversity-based transmission of rank 2.

Embodiment 1-6

In order to allow the base station to transmit uplink diversitytransmission to the UE and the UE to receive such an indication, the UEmay receive an indication of a plurality of SRS resources among SRSresources configured through RRC in advance from the base station.

In the NR system, the base station may detect a channel state in a beamdirection in which the UE performs transmission through an SRStransmitted by the UE and indicate again the SRS resources to the UE, sothat the UE may identify a beam direction required for uplink datatransmission. In addition, the UE may identify how many antenna ports ofthe codebook are used for transmission of the UE through the indicatedSRS resources and how codebook subset restriction of the correspondingcodebook is configured.

At this time, detailed information on the SRS required for SRStransmission may be configured. An SRS transmission band, a transmissionperiod, and a slot (or subframe or mini-slot) offset may be configured.Further, the number of antenna ports or the cyclic shift andtransmission comb for ZC sequence transmission may also be transmittedfor each SRS group.

In order to efficiently use SRS resources for the indication, some ofthe SRS resources configured through a higher layer such as RRC may beactivated in advance and then only some of the activated resources maybe indicated through DCI.

Particularly, in the case of a high frequency band, a data beam width ofthe UE becomes narrower due to reduction in a form factor, andaccordingly, support of a large number of beams and support of thenumber of SRS resources according thereto may be needed.

At this time, it is possible to optimize resources to be suitable forthe UE location and an optimal beam group by activating and deactivatingthe SRS resources. A method of actually transmitting the SRS may bedescribed below.

SRS resource configuration and trigger method 1: configures a pluralityof aperiodic SRS sources in advance, activate some of the configuredresources, and triggers some of the activated resources.

SRS resource configuration and trigger method 2: configures a pluralityof aperiodic SRS resources in advance and periodically transmitscorresponding CSI-RS resources according to activation untildeactivation.

SRS resource configuration and trigger method 1 is a method ofconfiguring a plurality of aperiodic SRS resources in advance,activating some of the configured resources, and triggering some of theactivated resources. For activation of the resources, the base stationmay transmit an activation signal through a MAC control element (CE)signal. Upon receiving a DCI trigger for corresponding SRS resourcetransmission from the base station, the UE receiving the activationsignal may transmit the corresponding SRS.

SRS resource configuration and trigger method 2 is a method ofconfiguring a plurality of semi-persistent SRS resources in advance andperiodically transmitting the corresponding SRS resources according toactivation until deactivation. For activation of the resources, the basestation may transmit an activation signal through a MAC CE signal.Further, the base station may activate or deactivate candidate resourcesthrough the MAC CE signal, and actual activation or deactivation may beperformed through some DCI of the activated candidate resources throughthe MAC CE signal.

FIG. 14B illustrates an example of an operation for activating SRScandidate resources through the MAC CE and actually activating SRScandidate resources through DCI. Referring to FIG. 14B, the base stationactivates report candidate resources through the MAC CE in step 1430. Inorder to receive and then activate the signal, the UE requires time X instep 1440, and then the UE receives DCI for activating report resourcesfrom the base station in step 1450. Thereafter, the UE receives DCI fordeactivating report resources in step 1460 and receives an MAC CE fordeactivating report candidate resources in step 1470. In order toreceive and then deactivate the signal, the UE requires time Y in step1480. For diversity transmission in <Embodiment 1-1> to <Embodiment 1-4>based on the SRS candidate resources, the UE may receive an indicationof a plurality of SRS resources or SRS sets. Further, in order toidentify a beam for precoder cycling in <Embodiment 1-1> to <Embodiment1-4>, a plurality of SRS resources may be applied to each cycling unit.For example, precoding applied to a UL DMRS 0 to support precodercycling illustrated in FIG. 8 may be transmitted on the basis of firstindicated SRS resources and precoding applied to a UL DMRS 1 may betransmitted on the basis of second indicated SRS resources. Theapplication may be equally performed on other embodiments, and adifferent number of SRS resources or SRS sets may be indicated accordingto the number of circulated precoders. Further, the plurality of SRSresources may be applied together with subband precoding.

FIG. 15 illustrate time and frequency resources used to transmit uplinkdata by a plurality of UEs.

As illustrated in FIGS. 15A to 15C, uplink transmission allocationvaries depending on a channel state of a UE. Particularly, transmissionpower in uplink is limited due to characteristics of a battery of the UEand hardware limitation.

Accordingly, it is required to consider characteristics of allocation ofresources different from those in downlink. The UE having a good channelstate may transmit uplink data using a wide frequency band and a shorttime as indicated by reference numeral 1510. This is because sufficientdata can be transmitted only with transmission power of the UE since achannel state between the UE and the base station is good. The UEtransmits data using somewhat limited frequency bands and an increasedtime as indicated by reference numeral 1520. This is because the UE hasa relatively worse channel state than the UE indicated by referencenumeral 1510. In uplink, power spectral density of the frequency may beincreased by decreasing the transmission band and increasing thetransmission time as illustrated in FIG. 15. Further, althoughtransmission power of the UE is limited within a specific time, aneffect of improving actual coverage of UE transmission data can beobtained by repeatedly using the same power. In addition, if the channelbetween the UE and the base station is very bad, resources may beallocated to transmit a signal for a long time in a very narrow band asindicated by reference numeral 1530.

As illustrated in FIG. 15, the characteristic of uplink transmission isdifferent according to each UE, and thus precoding-related informationrequired when the UE performs transmission may also be differentaccording to each band. Accordingly, the base station indicates one SRSif the UE supports the entire band precoding and the base stationindicates SRS resources or SRS resource sets which are the same as orsmaller than the number of subbands or the number of bandwidth partswhich corresponds to sets of subbands etc., thereby supporting of uplinktransmission of the UE. Further, the UE may identify how many antennaports of the codebook are used for transmission of the UE through theindicated SRS resources and how codebook subset restriction of thecorresponding codebook is configured.

The plurality of SRS resources or SRS sets may be indicated to the UEfrom the base station using a plurality of the same SRS resource or SRSset indication fields. Whether the indicated SRS resources or SRS setsare used for subband precoding or diversity-based transmission isprovided on the basis of a DCI field, a MAC CE, or an RRC field. Forexample, the corresponding SRS sets may be used for subband precoding ifthe DCI field is 0, and the corresponding SRS sets may be used fordiversity-based transmission if the DCI field is 1. Further, whether toperform subband precoding-based transmission or diversity-basedtransmission is configured through RRC or the MAC CE, and thecorresponding SRS resources may be used for the configured purposeaccording to the result of the configuration. That is, it may beunderstood that the beam is circulated on the frequency axis (in thecase of subband precoding) and on the time axis (in the case ofdiversity).

At this time, for the transmission, subband precoding or secondprecoding per each SRS resource may be transmitted through the MAC CE orRRC. Accordingly, it is possible to reduce DCI overhead and receiveprecoding information.

Further, the numbers of a plurality of configured SRS antenna ports areall the same or only one of the number of antenna ports may beconfigured. Unlike the base station supporting a relatively largernumber of antennas (for example, 16 ports or 32 ports), the UE has arelatively smaller number of antennas due to a form factor of thecorresponding UE. Accordingly, there may be little need to differentlyconfigure the number of corresponding antennas, and it is possible toreduce complexity depending on varying the number of antenna ports ofresources supported by subband precoding and also reduce UL DCI overheadthrough the same wideband TPMI by making the numbers of antenna ports ofall SRS resources the same.

The example in which the SRS resource field for subband precoding andthe diversity-based SRS resource field are supported based on the samefield and the indication of the corresponding field is different on thebasis of the DCI, MAC CE, and/or RRC field has been proposed, the SRSresource field may be shared with fields other than the diversity-basedfield and the subband precoding field. For example, in the case ofrank >1 transmission, if the indication of a plurality of SRS resourcesor SRS sets for supporting different beam corresponding to each layer ispossible, the indication may be performed using the same field.

Embodiment 1-7

The base station may indicate the use of diversity transmission to theUE through the following methods in order to determine whether the UEuses diversity transmission.

-   -   Diversity transmission use indication method 1: indication        through DCI    -   Diversity transmission use indication method 2: indicates RRC or        MAC CE    -   Diversity transmission use indication method 3: indication to        the UE through the number of SRS resources

Diversity transmission use indication method 1 is a method of indicatingthe use of diversity transmission through DCI. When the base stationschedules uplink data transmission for the UE, the base station maytransmit information such as the TRI, the wideband TPMI, and theresource allocation through UL DCI as described above. Further, the basestation may indicate whether diversity transmission is used through 1bit. For example, the base station indicates the use of one precoding orthe same number of precodings as that of ranks if the bit is 0 and theuse of diversity transmission or precoder cycling if the bit is 1.

When the UE receives an indication of diversity transmission through theone bit, preconfigured information, for example, through subband TPMIinformation within the same DCI, subband TPMI information of second DCI,or MAC CE, subband TPMI information configured in advance may beidentified, or through RRC, subband TPMI information configured inadvance may be identified. At this time, if the UE receives the subbandTPMI through the MAC CE or RRC, the corresponding subband TPMIinformation may be configured according to each SRS resource which canbe indicated to the UE or has been configured, and the UE may identifythe subband TPMI through the corresponding one bit information and theindicated SRS resources.

Diversity transmission use indication method 2 is a method of indicatingwhether diversity transmission is used through RRC or the MAC CE. Byconfiguring whether to use diversity transmission in the UE through RRCor the MAC CE, the UE may identify whether the corresponding diversitytransmission is used. In this case, there is an advantage in that anamount of information of UL DCI which the base station transmits to theUE is reduced and thus coverage of the UL DCI can be guaranteed.

Diversity transmission use indication method 3 is a method of indirectlyindicating whether diversity transmission is used through the number ofSRS resources indicated to the UE. As described above, in order toperform SRS-based diversity transmission, the indication of a pluralityof SRS resources or resource sets is needed. Accordingly, only when theplurality of corresponding SRS resources or resource sets are indicated,the UE can perform diversity transmission. Further, the operation can beperformed only when the operation is configured to be performed throughRRC. At this time, a DCI bit for the SRS indication may be determined bythe maximum number of SRS resources which can be indicated in order toreduce the number of blinding decodings of DCI. If the SRS indication isnot transmitted, non-transmission of the indication may be providedthrough a specifically fixed value (for example, 0 means that the SRS isnot indicated).

In addition, the diversity transmission use indication methods mayinclude a combination of a plurality of methods. For example, ifindication methods 2 and 3 are simultaneously satisfied (if the use ofdiversity transmission is configured in advance through RRC and thenumber of indicated and configured SRS resources is larger than apredetermined number), diversity transmission can be performed. Inanother example, if all of indication methods 1, 2, and 3 are satisfied,diversity transmission can be performed.

In order to indicate the plurality of SRS resources described above, SRSsets may be indicated using an indication field as shown in [Table 7].

TABLE 7 SRS indicator notification 00 SRS set 1 01 SRS set 2 10 SRS set3 11 SRS set 4

Information on which SRS resources are indicated by each SRS set throughRRC or the MAC CE may be configured through a bitmap. If the field isused, DCI overhead generated by the SRS resource indication can bereduced and SRS resources can be effectively indicated.

In addition, whether to indicate a plurality of SRS resources may beexpressed using one bit of DCI. As described above, one SRS resource isindicated when wideband precoding is supported. At this time, intransmission based on one SRS resource, a beam direction is moreimportant than in transmission based on a plurality of SRS resources,and accordingly, the larger degree of freedom may be needed. On theother hand, the indication of a plurality of SRS resources generates toomuch DCI overhead under the large degree of freedom. Accordingly, theSRS indication field may indicate one SRS resource if one bit is 0 onthe basis of the DCI field of one bit, and the SRS indication field mayindicate a plurality of SRS resources or the plurality of SRS resourcesare indicated using the plurality of SRS set indication fields similarto the example of [Table 7] if one bit is 1.

Embodiment 1-7

When <Embodiment 1-1> to <Embodiment 1-4> are applied to the UE, themethod may be differently applied according to a waveform Used by theUE. <Embodiment 1-1> and <Embodiment 1-4> cannot be supported if DFT-SOFDM is used, and the two embodiments can be applied if CP-OFDM is used.Accordingly, one or both of <Embodiment 1-1> and <Embodiment 1-4> can besupported if CP-OFDM is used and <Embodiment 1-2> and <Embodiment 1-3>can be supported if DFT-S OFDM is used. Further, all available diversitytransmission can be supported if CP-OFDM is used and only <Embodiment1-2> and <Embodiment 1-3> can be supported if DFT-S OFDM is used.

Embodiment 1-8

The relation between the precoding, the DMRS, and the SRS may be definedas follows.

-   -   Precoding, DMRS, and SRS relation definition method 1: the        relation is defined on the basis of the sequence indicated to        the UE through DCI.    -   Precoding, DMRS, and SRS relation definition method 2: the        relation is indirectly defined through SRS resource ID.    -   Precoding, DMRS, and SRS relation definition method 3: the        relation is directly defined to the UE by the base station        through RRC configuration or MAC CE configuration.

Precoding, DMRS, and SRS relation definition method 1 is a method ofdefining the relation is defined on the basis of the sequence indicatedto the UE through DCI. According to the method, precoding of a firstlayer is indicated through a first indicated DMRS port and SRS resourcesand precoding of a second layer is indicated through a second indicatedDMRS port and SRS resources on the basis of precoding indicated to theUE. That is, a beam according to precoding of a first layer indicated tothe UE and SRS resources is associated with a DMRS first indicated bythe base station. Through the method, the base station may have anadvantage of flexibly configuring diversity-based transmission in theDMRS port and the SRS resources without additional overhead of the UE.

Precoding, DMRS, and SRS relation definition method 2 is a method ofindirectly defining the relation through an SRS resource ID. That is,precoding of a low layer in the indicated precoding information isapplied to a DMRS port having a low port number among the indicatedDMRSs and an SRS resource having a low SRS resource ID. The method hasan advantage of reducing indication overhead and implementationcomplexity.

Precoding, DMRS, and SRS relation definition method 3 is a method ofdirectly defining the relation to the UE by the BS through RRC or MAC CEconfiguration. Which layer of precoding is mapped to the DMRS port maybe configured in advance according to the order indicated through theRRC field.

In addition, a plurality of methods may be used together for theprecoding, DMRS, and SRS relation definition method. For example, acombination of definition methods 1 and 2 is a method of applying a DMRSport having a low port number and precoding of a low layer to the DMRSand indicating an SRS through an indicated order. Further, a method ofapplying the port having a low number and precoding of a low layer tothe DMRS and applying configuration by RRC or MAC CE to the SRS may beused.

According to the embodiments of the disclosure, various sequences suchas a gold sequence, a pseudo random noise (PN) sequence, a ZC sequence,and a constant amplitude zero autocorrelation waveform) sequence may beapplied to the DMRS. Further, according to the embodiment, it is assumedthat the DMRS pattern is configured on 8 REs in one symbol, but variouspatterns such as 6 REs may be used.

The embodiments are made based on uplink diversity transmission but maybe used for downlink and sidelink diversity transmission.

In order to apply the embodiments, layer shifting may be considered inthe case of transmission of rank larger than 1. For example, in the caseof rank 2, it is assumed that DMRS ports 0 and 1 are sequentially usedfor layers 0 and 1 if transmission is performed using precoder 0, andDMRS ports 1 and 0 are sequentially used for layers 0 and 1 iftransmission is performed using precoder 1. Such a principle may beequally applied to transmission of a higher rank larger than or equal to3.

Further, ranks available for the diversity transmission may be limited.This is because the corresponding diversity gain decreases as the numberof ranks increases in the diversity transmission.

In order to implement the above-described embodiments of the disclosure,a transmitter, a receiver, and a processor of each of the UE and thebase station are illustrated in FIGS. 16 and 17. The receiver, theprocessor, and the transmitter of the base station and the UE shouldoperate according to embodiments in order to implement the embodiments.

FIG. 16 is a block diagram illustrating an internal structure of the UEaccording to an embodiment of the disclosure. As illustrated in FIG. 16,the UE according to the disclosure may include a UE receiver 1610, a UEtransmitter 1620, and a UE processor 1630. The UE receiver 1610 and theUE transmitter 1620 may be collectively referred to as a transceiver inembodiments of the disclosure. The transceiver may transmit and receivea signal to/from the base station. The signal may include controlinformation and data. To this end, the transceiver includes an RFtransmitter that up-converts and amplifies a frequency of a transmittedsignal, an RF receiver that low-noise amplifies a received signal anddown-converts the frequency, and the like. Also, the transceiver mayreceive a signal through a radio channel, output the signal to the UEprocessor 1630, and transmit the signal output from the UE processor1630 through the radio channel.

The UE processor 1630 may control a series of processes such that the UEoperates according to the above-described embodiments of the disclosure.For example, the UE receiver 1610 may receive a signal includingindication signal transmission timing information from the base station,and the UE processor 1630 may perform control to analyze signaltransmission timing. Thereafter, the UE transmitter 1620 transmits asignal at the timing.

FIG. 17 is a block diagram of the internal structure of a base station(BS) according to an embodiment of the disclosure. As illustrated inFIG. 17, the base station according to the disclosure may include a basestation receiver 1710, an base station transmitter 1720, and an basestation processor 1730. The base station receiver 1710 and the basestation transmitter 1720 are commonly called a transceiver in theembodiments of the disclosure. The transceiver may transmit and receivea signal to/from the UE. The signal may include control information anddata. To this end, the transceiver includes an RF transmitter thatup-converts and amplifies a frequency of a transmitted signal, an RFreceiver that low-noise amplifies a received signal and down-convertsthe frequency, and the like. Also, the transceiver may receive a signalthrough a radio channel, output the signal to the base station processor1730, and transmit the signal output from the base station processor1730 through the radio channel.

The base station processor 1730 may control a series of processes suchthat the base station operates according to the above-describedembodiments of the disclosure. For example, the base station processor1730 may determine a processing method and perform control to generateprocessing method information to be transmitted to the UE. Thereafter,the base station transmitter 1720 may transmit the information to theUE.

Further, according to an embodiment of the disclosure, the base stationprocessor 1730 may perform control to generate downlink controlinformation including reference signal processing information for uplinkprecoding.

Second Embodiment

A wireless communication system has developed to be a broadband wirelesscommunication system that provides a high speed and high quality packetdata service, like the communication standards, for example, high speedpacket access (HSPA) of 3GPP, long term evolution (LTE) or evolveduniversal terrestrial radio access (E-UTRA), LTE-advanced (LTE-A), highrate packet data (HRPD) of 3GPP2, ultra mobile broadband (UMB), and802.16e of IEEE, or the like, beyond the voice-based service provided atthe initial stage. 5G or new radio (NR) communication standard isresearched as the 5^(th) generation wireless communication system.

An LTE system, which is a representative example of the broadbandwireless communication system, employs an orthogonal frequency divisionmultiplexing (OFDM) scheme for a downlink (DL), and employs a singlecarrier frequency division multiple access (SC-FDMA) scheme for anuplink (UL). The uplink is a radio link through which a user equipment(UE) (or a mobile station (MS)) transmits data or a control signal to anbase station (BS) (or an eNode B (eNB)), and the downlink is a radiolink through which the base station transmits data or a control signalto the UE. In such a multi-access scheme, time-frequency resources forcarrying data or control information are allocated and operated in amanner to prevent overlapping of resources, that is, to establishorthogonality, between users so as to identify data or controlinformation of each user. Hereinafter, the LTE system may include LTEand LTE-A systems.

When decoding fails at the initial transmission, the LTE system employshybrid automatic repeat request (HARQ) that retransmits thecorresponding data in a physical layer. In the HARQ scheme, when areceiver does not accurately decode data, the receiver transmitsinformation (negative acknowledgement: NACK) informing a transmitter ofa decoding failure and thus the transmitter may re-transmit thecorresponding data on the physical layer. The receiver combines the datare-transmitted by the transmitter with the data of which the previousdecoding failed, thereby increasing the data reception performance.Also, when the receiver accurately decodes data, the receiver transmitsinformation (acknowledgement: ACK) informing the transmitter of decodingsuccess, so that the transmitter may transmit new data.

FIG. 18 illustrates the basic structure of a time-frequency region whichis a radio frequency region in which a data or control channel istransmitted in downlink of the LTE system.

In FIG. 18, the horizontal axis indicates a time region and the verticalaxis indicates a frequency region. A minimum transmission unit in thetime region is an OFDM symbol. One slot 1806 consists of N_(symb) OFDMsymbols 1802 and one subframe 1805 consists of 2 slots. The length ofone slot is 0.5 ms, and the length of one subframe is 1.0 ms. A radioframe 1814 is a time region interval consisting of 10 subframes. Aminimum transmission unit in the frequency region is a subcarrier, andthe bandwidth of an entire system transmission band consists of a totalof N_(BW) subcarriers 1804.

A basic unit of resources in the time-frequency region is a resourceelement (RE) 1802 and may be indicated by an OFDM symbol index and asubcarrier index. A resource block (RB or physical resource block (PRB))1808 is defined by N_(symb) successive OFDM symbols 1802 in the timeregion and N_(RB) successive subcarriers 1810 in the frequency region.Therefore, one RB 1808 includes N_(symb)×N REs 1812. In general, aminimum transmission unit of data is the RB unit. In the LTE system,generally, N_(symb)=7 and N_(RB)=12. N_(BW) is proportional to a systemtransmission bandwidth. A data transmission rate increases in proportionto the number of RBs scheduled to the UE.

The LTE system defines and operates 6 transmission bandwidths. In thecase of a frequency division duplex (FDD) system that operates byseparating a downlink and an uplink by frequency, a downlinktransmission bandwidth and an uplink transmission bandwidth may bedifferent from each other. A channel bandwidth may indicate an RFbandwidth corresponding to a system transmission bandwidth. [Table 1]indicates the relationship between a system transmission bandwidth and achannel bandwidth defined in the LTE system. For example, when the LTEsystem has a channel bandwidth of 10 MHz, the transmission bandwidth mayconsist of 50 RBs.

TABLE 8 Channel 1.4 3 5 10 15 20 bandwidth BW_(Channel) MHz Transmissionbandwidth 6 15 25 50 75 100 configuration N_(RB)

FIG. 19 illustrates the basic structure of a time-frequency region whichis a radio resource region in which a data or control channel istransmitted in uplink of the LTE system according to the prior art.

Referring to FIG. 19, the horizontal axis indicates the time region andthe vertical axis indicates the frequency region. A minimum transmissionunit in the time region is an SC-FDM system 1902 and one slot 1906consists of N_(symb) SC-FDMA symbols. One subframe 1905 consists of twoslots. A minimum transmission unit in the frequency region is asubcarrier and an entire system transmission band (transmissionbandwidth) 1904 consists of a total of N_(BW) subcarriers. N_(BW) has avalue, which is proportional to a system transmission band.

A basic unit of resources in the time-frequency region is a resourceelement (RE) 1912 and may be defined by an SC-FDMA symbol index and asubcarrier index. A resource block (RB) 1908 is defined by N_(symb)successive SC-FDMA symbols in the time region and N_(BW) successivesubcarriers in the frequency region. Therefore, one RB consists ofN_(symb)×N_(R)B REs. In general, a minimum transmission unit of data orcontrol information is an RB. A PUCCH is mapped to a frequency regioncorresponding to 1 RB, and may be transmitted during one subframe.

FIG. 20 illustrates radio resources of one RB which is the minimum unitof scheduling in downlink of the LTE system. In radio resourcesillustrated in FIG. 20, a plurality of different types of signalsdescribed below may be transmitted.

1. Cell specific RS (CRS) 2000: refers to a reference signalperiodically transmitted for all UEs belonging to one cell and may beused by a plurality of UEs in common.

2. Demodulation reference signal (DMRS) 2010: refers to a referencesignal transmitted for a specific UE and is transmitted only when datais transmitted to the corresponding UE. The DMRS may include a total of8 DMRS ports. In the LTE system, port 7 to port 14 correspond to DMRSports, and the ports maintain orthogonality to prevent interferencetherebetween through CDM or FDM.

3. Physical downlink shared channel (PDSCH) 2020: used when the basestation transmits traffic to the UE through a data channel transmittedthrough downlink and transmitted using an RE where a reference signal isnot transmitted in a data region of FIG. 20.

4. Channel status information reference signal (CSI-RS) 2040: refers toa reference signal transmitted for UEs belonging to one cell and is usedto measure a channel status. A plurality of CSI-RSs may be transmittedin one cell.

5. Other channels (a physical hybrid-ARQ indicator channel (PHICH), aphysical control format indicator channel (PCFICH), and a physicaldownlink control channel (PDCCH)) 2030: used when the UE providescontrol information required for receiving a PDSCH or to transmitACK/NACK for operating HARQ of uplink data transmission. They aretransmitted in a control region 2050.

FIG. 21 illustrates an example of a method of generating a DMRS. DMRSsare generated from a pseudo-random (PN) sequence based on a goldsequence of the length 31 as illustrated in FIG. 21. More specifically,as illustrated in FIG. 21, a PN sequence C(n) may be generated byconcatenating a first m-sequence x₁(n) generated from a polynomialD31+D3+1 of a higher register and a second m-sequence x₂(n) generatedfrom a polynomial D31+D3+D2+D+1 of a lower register, and the processormay be expressed by [Equation 9].c(n)=(x ₁(n+N _(C))+x ₂(n+N _(C)))mod 2x ₁(n+31)=(x ₁(n+3)+x ₁(n))mod 2x ₂(n+31)=(x ₂(n+3)+x ₂(n+2)+x ₂(n+1)+x ₂(n))mod 2  [Equation 9]

N_(c)=1600 and register initialization is performed as follows.

The first m-sequence x₁(n) generated from the higher register isinitialized into a fixed pattern of x₁(0)=1, x₁(n)=0, n=1, 2, . . . ,30.

The second m-sequence x₂(n) generated from the lower register isinitialized into [Equation 10] below under a scrambling conditionrequired by each signal.

$\begin{matrix}{c_{init} = {\sum\limits_{i = 0}^{30}\;{{x_{2}(i)} \cdot 2^{i}}}} & \left\lbrack {{Equation}\mspace{14mu} 10} \right\rbrack\end{matrix}$

More specifically, in the case of the DMRS, [Equation 10] may beexpressed by [Equation 11] below in order to transmit a DMRS port p=5.c _(init)=(└n _(s)/2+1┘)·(2N _(ID) ^(cell)+1)·2¹⁶ +n _(RNTI)  [Equation11]

In the above equation, n_(s) denotes a slot number within a transmissionframe and n_(RNTI) denotes a UE ID. N_(ID) ^(cell) denotes a cell ID.Unlike this, [Equation 10] may be expressed by [Equation 12] below inorder to transmit a DMRS port p∈{7, 8, . . . , 14}.c _(init)=(└n _(s)/2┘+1)·(2n _(ID) ^((n) ^(SCID) ⁾+1)+n_(RNTI)  [Equation 12]

In the equation, n_(s) denotes a slot number within a transmissionframe, and n_(SCID) denotes a scrambling ID having a value of 0 or 1 andit is assumed that the value of the scrambling ID is 0 unless mentionedspecifically. n_(ID) ^((i)),i=0,1 is determined as follows.

-   -   n_(ID) ^((i))=N_(ID) ^(cell) if no value for n_(ID) ^(DRMS,i) is        provided by higher layers or if DCI format 1A, 2B or 2C is used        for the DCI associated with the PDSCH transmission    -   n_(ID) ^((i))=n_(ID) ^(DRMS,i) otherwise

As described above, in the case of the DMRS, initialization is performedin every subframe, and a reference signal for transmitting a DMRS portp∈{7, 8, . . . , 14} is expressed by [Equation 13].

$\begin{matrix}{{{r(m)} = {{\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {2m} \right)}}} \right)} + {j\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {{2m} + 1} \right)}}} \right)}}},{m = \left\{ {{{\begin{matrix}{0,1,\ldots\;,{{12N_{RB}^{\max,{DL}}} - 1},{normalcyclicprefix}} \\{0,1,\ldots\;,{{16N_{RB}^{\max,{DL}}} - 1},{extendedcyclicprefix}}\end{matrix}\mspace{76mu} N_{RB}^{\max,{DL}}} = 110},} \right.}} & \left\lbrack {{Equation}\mspace{14mu} 13} \right\rbrack\end{matrix}$

which indicates a maximum number of RBs supported for downlink in theLTE system. In the case of the LTE system, since a fixed DMRS pattern isused for each of a normal CP and an extended CP, the DMRS sequence asshown in [Equation 13] may be generated in consideration of the numberof DMRS REs per PRB.

However, unlike the LTE system, the 5G wireless communication systemconsiders support of the DMRS structure which can be configured as wellas an increased cell ID, an increased channel bandwidth, support ofvarious subcarrier spacings, support of slot-based transmission and slotaggregation, and DMRS bundling on the time. If such various matters areconfigured, the DMRS sequence generation method may also be different.The DMRS sequence of the NR system may be UE-specifically generated,transmission and reception point (TRP)-specifically generated, orresource-specifically generated. Accordingly, the DMRS operation methodmay be different. Therefore, the disclosure proposes a DMRS sequencegeneration method reflecting such matters.

Hereinafter, an embodiment of the disclosure will be described in detailwith reference to the accompanying drawings. Although embodiments of thedisclosure are described as examples of the LTE or LTE-A system, theembodiments of the disclosure may be also applied to other communicationsystems having a similar technical background or channel form. Forexample, 5 generation mobile communication technology (5G, new radio(NR)) developed after LTE-A may be included therein. In the NR system,the basic structure of the time-frequency region in which downlink anduplink signals are transmitted may be different from that of FIGS. 18and 19, and the type of the signal transmitted in downlink and uplinkmay also be different. However, an embodiment of the disclosure can beapplied to other communication systems through some modificationswithout departing from the scope of the disclosure on the basis ofdetermination of those skilled in the art.

In the following description of the disclosure, a detailed descriptionof known functions or configurations incorporated herein will be omittedwhen it may make the subject matter of the disclosure rather unclear.The terms which will be described below are terms defined inconsideration of the functions in the disclosure, and may be differentaccording to users, intentions of the users, or customs. Therefore, thedefinitions of the terms should be made based on the contents throughoutthe specification.

Hereinafter, the base station is the entity that allocates resources tothe UE and may be one of an eNode B, a Node B, a base station (BS), aradio access unit, an base station controller, and a node on a network.The UE may include a user equipment (UE), a mobile station (MS), acellular phone, a smartphone, a computer, and a multimedia systemcapable of performing a communication function. In the disclosure, adownlink (DL) refers to a wireless transmission path of a signal thatthe base station transmits to the UE, and an uplink (UL) refers to awireless transmission path of a signal that the UE transmits to the basestation.

In the following description, a demodulation reference signal (DMRS) isa reference signal having a characteristic by which the UE can performdemodulation without additional reception of precoding information aftera reference signal to which UE-specific precoding is applied istransmitted, and the name thereof used in the LTE system is directlyused. However, the term DMRS may be exchangeable with another termaccording to the user's intention and for the purpose of the use of areference signal. For example, the DMRS may be interchangeable with aUE-specific signal (UE-specific RS) or a dedicated reference signal(dedicated RS).

More specifically, the term DMRS is only a specific example to easilydescribe the technology of the disclosure and help understanding of thedisclosure, and it is apparent to those skilled in the art that theoperation can be performed through other terms based on the technicalidea of the disclosure. The term single-user multi-input andmulti-output (SU-MIMO) or multi-user MIMO (MU-MIMO) is also used toeasily describe the technology of the disclosure and help understandingof the disclosure, and it is apparent to those skilled in the art thatthe operation of the disclosure can be performed through other terms orwithout the terms.

Embodiment 2-1

<Embodiment 2-1> describes a method of transmitting DMRSs according to aplurality of orthogonal DMRS antenna ports.

Specifically, the DMSR structure proposed by the disclosure will bedescribed with reference to FIGS. 22A and 22B. FIG. 22A illustrates anexample of the unit DMRS structure proposed by the disclosure. The unitDMRS structure based on one OFDM symbol is advantageous to configure thelocation of a reference signal for various transmission time intervals(TTIs), support low latency, configure the location of a referencesignal for URLLC, and in terms of scalability such as antenna portextension.

As illustrated in FIG. 22A, 12 subcarriers may be included in one OFDMsymbol on the basis of a PRB which is a minimum transmission unit ofdata. Density of a DMRS subcarrier (SC) can be configured in one OFDMsymbol as indicated by reference numerals 2210, 2220, and 2230.Reference numerals 2210 and 2220 indicate DMRS structures in which fourand eight DMRS SCs are included in twelve subcarriers, respectively, andreference numeral 2230 indicates the DMRS structure in which allsubcarriers are used as DMRS SCs. The use of the DMRS structure proposedby FIG. 22A of the disclosure is not limited to a data channel.

The DMRS structure 2210 may be used in an environment in which a smallnumber of DMRS SCs are configured and thus an antenna port of a lowernumber is supported or a channel change on the frequency is small. TheDMRS structure 2210 may be used for a mini-slot or a control channelrequiring a relatively lower DMRS density. In contrast to this, the DMRSstructure 2220 may be used in an environment in which a large number ofDMRS SCs are configured and thus an antenna port of a higher number issupported or a channel change on the frequency is large. Further, theDMRS structure 2220 may be used to improve the channel estimationperformance by increasing the DMRS density in a low signal to noiseratio (SNR) area.

While a fixed DMRS pattern may be used for each of a normal CP, anextended CP, and a multicast broadcast single frequency network (MBSFN)subframe in the LTE system, the proposed DRMS pattern 2220 may be usedfor the extended CP or the MBSFN DMRS in the NR system. Configuring theDMRS with an even number of DMRS SCs as indicated reference numerals2210 and 2220 may have advantages in that no orphan RE is made ifspacing frequency block coding (SFBC) of a transmit diversity scheme isconsidered.

An SC which is not used as the DMSR SC in the DMRS structures 2210 and2220 may be used for data or another signal such as another referencesignal or may be empty for DMRS power boosting. If the SC which is notused as the DMRS SC is empty for DMRS power boosting, the performance ofDMRS channel estimation in a low SNR region may be improved. Further,the DMRS structures 2210 and 2220 have subcarriers that do not transmitthe DMRS, and thus a portion thereof may be used as a direct current(DC) subcarrier.

For example, under consideration of various numerologies, a method ofusing the DC subcarrier together with the DMRS structure 2220 will bedescribed through reference numerals 2240, 2250, and 2260 of FIG. 22B.FIG. 22B illustrates an example in which DC subcarriers are arrangedaccording to the DMRS structure proposed by the disclosure. The DMRSstructure 2210 may use the same method as indicated by referencenumerals 2240, 2250, and 2260.

In the situation in which various numerologies can be multiplexed on thetime in the NR system, the case in which a signal is transmitted withsubcarrier spacing of f0 configured at time t0, the case in which asignal is transmitted with subcarrier spacing of 2*f0 configured at timet1, and the case in which a signal is transmitted with subcarrierspacing of 4*f0 configured at time t2 are illustrated. As illustrated inreference numerals 2240, 2250, and 2260, if a specific SC which is notused as the DMRS SC is configured as a DC subcarrier, the DMRS structureof the disclosure has advantages in that there is no need to change thelocation of the DC subcarriers according to subcarrier spacing changingover time. However, since the DMRS is transmitted in all subcarriers inthe DMRS structure 2230, some of the subcarriers are needed to bepunctured to transmit the DC.

The DMRS SCs illustrated in reference numerals 2210 to 2230 may begenerated on the basis of the pseudo-random sequence or the Zadoff-Chu(ZC) sequence. More specifically, the DMRS structures 2210 and 2220 maybe used in a cyclic prefix (CP)-OFDM system. Further, inuplink/downlink, the DMRS structures may be configured and used at thesame time-frequency location. If uplink and downlink have the same DMRSstructure, uplink and downlink DMRS ports can be allocated to beorthogonal, so that interference cancellation performance can beimproved by more increasing channel estimation performance in a flexibleduplex environment.

On the other hand, similar to the LTE system, the DMRS structure 2230 isbased on the Zadoff-Chu (ZC) sequence, and may be used in uplink in thecase of a discrete Fourier transform-spread-OFDM (DFT-s-OFDM) system. Inthis case, similar to the LTE system, a low peak-to-average power ratio(PAPR) can be obtained. However, the disclosure is not limited to themethod of using the proposed structure 2210 to 2230. For example, theDMRS structure 2230 may be used for all of the CP-OFDM, the DFT-s-OFDM,and the uplink/downlink.

FIG. 23 illustrates an example of a method of mapping antenna ports tothe unit DMRS structure proposed by FIG. 22A. In FIG. 23, antenna portsare expressed as p=A, B, C, D, . . . , for convenience. However, antennaport numbers may be expressed as other numbers. Mapping of the antennaports is to support transmission and ranks of a plurality of layers.Accordingly, the antenna port mapping described below may be relatedwith another term “layer transmission” or “rand support”.

Specifically, reference numerals 2300 and 2305 indicate the cases inwhich two antenna ports are mapped to the DMRS structure 2210. Referencenumeral 2300 indicates a method of mapping two antenna ports p=A, B in afrequency division multiplexing (FDM) scheme and a code divisionmultiplexing (CDM) scheme through application of an orthogonal covercode (OCC) having a length of 2, and reference numeral 2300 indicates amethod of mapping two antenna ports p=A, B without application of theOCC. Specifically, reference numerals 2310 and 2315 indicate the casesin which two antenna ports are mapped to the DMRS structure 2220. Sincethe DMRS 2220 has a higher density of the reference signal compared tothe DMRS 2210, channel estimation performance can be improved. Referencenumeral 2310 indicates the method of mapping two antenna ports p=A, B inthe FDM and CDM schemes through application of the OCC having a lengthof 2, and reference numeral 2315 illustrates the method of mapping twoantenna ports p=A, B in the FDM scheme without application of the OCC.

Reference numerals 2320 and 2325 indicate the cases in which fourantenna ports are mapped to the DMRS structure 2220. At this time, inorder to improve channel estimation performance, subcarriers throughwhich the DMRS is not transmitted in the DMRS structure 2220 are emptyand used for DMRS power boosting. Reference numeral 2320 indicates amethod of mapping four antenna ports p=A, B, C, D through application ofthe FDM scheme and the OCC having a length of 2, and reference numeral2325 illustrates a method of mapping four antenna ports p=A, B, C, D inthe FDM scheme without application of the OCC. Reference numerals 2330and 2335 indicate the cases in which six antenna ports are mapped to theDMRS structure 2220. At this time, in order to improve channelestimation performance, subcarriers through which the DMRS is nottransmitted in the DMRS structure 2220 are empty and used for DMRS powerboosting. Reference numeral 2330 indicates a method of mapping sixantenna ports p=A, B, C, D, E, F in the FDM and CDM schemes throughapplication of the OCC having a length of 2, and reference numeral 2335illustrates a method of mapping six antenna ports p=A, B, C, D, E, F inthe FDM scheme without application of the OCC.

The methods of mapping the antenna ports as indicated by referencenumerals 2330 and 2335 have characteristics that a density of referencesignals (RSs) for each antenna port is not consistent unlike the antennaport mapping method described above. This is because every UE has adifferent channel state in the method designated to allocate antennaports for MU-MIMO, in which case a port having a low RS density may beallocated to a UE having a good channel state and a port having a highRS density may be allocated to a UE having a bad channel state.

Reference numerals 2340 and 2345 indicate the cases in which eightantenna ports are mapped to the DMRS structure 2220. At this time, inorder to improve channel estimation performance, subcarriers throughwhich the DMRS is not transmitted in the DMRS structure 2220 are emptyand used for DMRS power boosting. Reference numeral 2340 indicates amethod of mapping eight antenna ports p=A, B, C, D, E, F, G, H in theFDM and CDM schemes through application of the OCC having a length of 2,and reference numeral 23000 illustrates a method of mapping eightantenna ports p-A, B, C, D, E, F, G, H in the FDM scheme withoutapplication of the OCC. The application of the OCC to the frequencyregion has advantages in that there is no power imbalance problem inreference numerals 2300, 2310, 2320, 2330, and 2340. In the LTE system,if the OCC is applied to the time region, the power imbalance problemmay occur and thus different OCCs are used for every PRB within twoPRBs.

Last, reference numeral 2350 illustrates the DMRS structure 2230. In theDMRS structure 2230, 12 subcarriers are all used as DMRSs, so that amethod of supporting orthogonal DMRS antenna ports using the Zadoff-Chu(ZC) sequence may be considered. At this time, like in the LTE system,based on the assumption that subcarrier spacing is 15 kHz, a maximum ofeight orthogonal antenna ports may be supported through application ofeight cyclic shift (CS) fields. In another method using the DMRSstructure 2230, a method of supporting four orthogonal antenna portsthrough application of the FDM scheme at four-subcarrier spacing may beconsidered. The disclosure is not limited to the methods of mapping theantenna ports to the proposed DMRS structures 2300 to 2350.

FIG. 24 illustrates an example of a method of mapping a larger number ofantenna ports to the unit DMRS structure proposed by FIG. 23. In orderto map a larger number of antenna ports, the DMRS may be configured toadditionally apply time division multiplexing (TDM), FDM, and/or CDM tothe unit DMRS structure of FIG. 22A. For example, as indicated byreference numerals 2410 and 2420, a larger number of antenna ports canbe mapped through TDM of the structure 2220 on the time. If orthogonalantenna ports are extended using TDM, there is an advantage in that theRS density on the frequency is maintained, but there is a disadvantagein that the DMRS density is increased in the transmission unit (onePRB).

In order to maintain the low DMRS density in the transmission unit, amethod of extending orthogonal antenna ports using FDM or CDM based onthe assumption that a high rank is supported in an environment in whicha channel state is very good and selectivity of a channel on thefrequency is low may be considered. For example, a larger number ofantenna ports can be mapped through FDM of the structure 2220 on thefrequency as indicated by reference numerals 2430 and 2440. However, ifthe number of antenna ports is extended using FDM, there may be adisadvantage in that the transmission unit is extended to several PRBs.A larger number of antenna ports can be mapped through application of anOCC having an extended length as indicated by reference numerals 2450and 2460. More specifically, reference numeral 2450 indicates a methodof multiplexing eight antenna ports through the OCC having the length of8 as indicated in the structure 2220, and reference numeral 2460indicates a method of multiplexing twelve antenna ports through the OCChaving the length in the structure 2230. The OCC may be generated as aWalsh-Hadamard code.

If all subcarriers are configured as the DMRS SCs as indicated byreference numeral 2230, various antenna port extensions can be performeddepending on the antenna port mapping method applied to the structure2230 as described above. If it is assumed that subcarrier spacing is 15kHz and eight orthogonal antenna ports are supported by cyclic-shiftingthe ZC sequence in reference numeral 2230, extension to 16 orthogonalantenna ports is possible through application of TDM as indicated byreference numeral 2140. If FDM is used at an interval of foursubcarriers in reference numeral 2230, a maximum of four orthogonalantenna ports may be supported, but if TED is considered as indicated byreference numeral 2410, a maximum of eight orthogonal antenna ports maybe supported. Alternatively, as indicated by reference numeral 2420, ifadditional TDM is considered, a maximum of 12 orthogonal antenna portsmay be supported.

The disclosure is not limited to the antenna port extension methodpresented by FIG. 24. The antenna port extension method can be appliedthrough a combination of TDM, FDM, and CDM, and orthogonal antenna portscan be extended through various methods. For example, as describedabove, if the antenna ports are extended using only TDM as indicated byreference numeral 2410 or 2420, there is a disadvantage in that the DMRSdensity increases in the transmission unit. In a method of compensatingfor the disadvantage, TDM may be applied to contiguous two slots asindicated by reference numeral 2470 and CDM using an OCC having a lengthof 4 may be applied to contiguous two slots as indicated by referencenumeral 2480. The above described is made on the basis of two slots asindicated by reference numerals 2470 and 2480, but the time unit towhich TDM or CDM is applied in reference numerals 2470 and 2480 is notlimited to the slot.

If the DMRS is generated with the ZC sequence unlike the method ofmapping a maximum of eight antenna ports through the application of theOCC having the length of 8 as indicated by reference numeral 2450,additional antenna ports can be supported using the CS as indicated byreference numeral 2490. For example, if the CS is used in the case ofmultiplexing to four antenna ports through FDM and CDM as indicated byreference 2320, additional antenna port extension is possible. If fourCS field are made, antenna ports may be extended to a maximum of 16. Ifthe CS is used instead of the OCC as indicated by reference numeral2490, there is an advantage in that the RS density on the frequency ismaintained.

In the 5G communication system, a plurality of DMRS structures can beconfigured. For example, the configurable DMRS structures may be dividedinto a front-loaded DMRS and an extended or additional (hereinafter,extended) DMRS.

Specifically, the front-loaded DMRS is a DMRS located at a front part ofa NR-PDSCH for rapid data decoding and may include one or two adjacentOFDM symbols. Further, the front-loaded DMRS is located at the frontpart of the NR-PDSCH and the location thereof may be fixed or flexible.For example, if the location of the front-loaded DMRS is determined tobe a start first symbol of the NR-PDSCH, the front-loaded RS may beflexibly changed by an area of an NR-PDCCH. Advantages of the cases inwhich the location of the front-loaded DMRS is fixed and flexible willbe described. If the location of the front-loaded DMRS is fixed, it maybe assumed that a DMRS of a next cell is always transmitted at the samelocation. However, the front-loaded DMRS may be weak at decoding latencyif an area of a control channel can be configured or if a DMRS of a datachannel is not located earlier in a subframe in which the controlchannel is not transmitted.

If the location of the front-loaded DMRS is flexible, the front-loadedRS is always located at a front part of the data channel, and thus thereis an advantage in terms of decoding latency. However, as the locationof the front-loaded RS varies, the DMRS location in cells is not fixedand there may be a problem about interference control and operation ofan advanced receiver. To this end, a method of introducing networksignaling may be additionally considered, but a method of configuring afixed DMRS location is generally more advantageous for system operation.For the reason, a detailed method of configuring the fixed location ofthe front-loaded DMRS is proposed.

FIG. 25 illustrates the location of the front-loaded DMRS in the case inwhich a slot length is 7 or 14 OFDM symbols. The configuration of thelocation of the front-loaded DMRS may be determined by an area of thecontrol channel. If the area of the control channel consists of amaximum of two OFDM symbols, the front-located DMRS is located at athird OFDM symbol as indicated by reference numeral 2510. If the area ofthe control channel consists of a maximum of three OFDM symbols, thefront-located DMRS is located at a fourth OFDM symbol as indicated byreference numeral 2520. As described above, if the location of thefront-loaded DMRS is determined by the maximum number of areas of thecontrol channel which can be configured, there may be a loss to reducedecoding latency when the control channel is not configured in all theareas.

Accordingly, as an extended method, the disclosure proposes anothermethod of configuring the location of the front-loaded DMRS. Forexample, if the area of the control channel consists of a maximum of twoOFDM symbols, an operation of fixing the front-loaded DMRS to a thirdOFDM symbol as indicated by reference numeral 2510 and an option offixing the front-loaded DMRS to a first OFDM symbol as indicated byreference numeral 2530 may be configured together. If such two optionsare configured according to circumstances, a disadvantage of the case inwhich the location of the front-loaded DMRS is fixed may be compensatedfor. Specifically, the configuration of a plurality of locations of thefront-loaded DRMS may be performed in various ways. For example, amethod of semi-static configuration through higher layer signaling suchas RRC may be considered. In another method, the location may beconfigured through system information such as a master information block(MIB) or a system information block (SIB). Further, a method ofdynamically configuring the location through DCI may be considered.Unlike this, the location may be configured through semi-persistencescheduling (SPS).

Subsequently, the extended DMRS will be described. The front-loaded DRMShas difficulty in accurately estimating a channel since it is notpossible to track a channel rapidly varying on the time in a highDoppler state. Further, it is not possible to correct a frequency offsetwith the front-loaded DMRS alone. Accordingly, for the reason, it isrequired to transmit an additional DMRS after the front-loaded DRMS inthe slot.

FIG. 26 illustrates the location at which the extended DMRS istransmitted in the case in which the slot length is 7 or 14 OFDMsymbols. FIG. 26 illustrates the extended DRMS for each of referencenumerals 2510, 2520, and 2530 showing the locations of the front-loadedDRMS. The location of the extended DMRS is configured to avoid thelocation at which the CRS is transmitted in the LTE system as indicatedby reference numerals 2610 to 2660. This may have an advantage in termsof influence by an LTE-NR coexistence state. However, in the case ofreference numerals 2670 to 2690, the location of the front-loaded DMRSoverlaps the location at which the CRS is transmitted in the LTE systemlike in reference numeral 2530.

While the number of locations of the extended DMRS may be configured asone as illustrated in FIG. 26 if the slot length is 7 OFDM symbols, thenumber of locations of the extended DMRS may need to be configured astwo according to a Doppler state if the slot length is 14 OFDM symbols.For example, the location of the extended DMRS may be configured asindicated by reference numeral 2620 in an environment in which a channelchanges rapidly and the location of the extended DMRS may be configuredas indicated by reference numeral 2630 in an environment in which achannel changes very rapidly.

The embodiment of FIGS. 25 and 26 illustrates the basis location of theDMRS based on the unit DMRS structure illustrated in FIG. 22, and thelocation of the DMRS may be additionally configured if the unit DMRSstructure is extended for antenna port extension as described withreference to FIG. 24. In the case of the extended DMRS, as a pluralityof DMRSs are configured on the time, DMRS overhead may be generated.Accordingly, in this case, it is possible to reduce DMRS overhead byconfiguring the DMRS having a low density on the frequency as indicatedby reference numeral 2210.

Hereinafter, a method by which the base station configures the DMRSstructure in consideration of various DMRS structures according to thedisclosure will be described. Specifically, according to the disclosure,as the number of supported orthogonal antenna ports increases, a DMRSport multiplexing method may be different. Further, different RSdensities may be configured on the frequency in the unit DMRS structure.A front-loaded RS structure and an extended RS structure on the timelike the extended DMRS may be configured. Accordingly, if the basestation configures a DMRS structure suitable for a transmissionenvironment, a configuration thereof should be signal to the UE in orderto allow the UE to accurately perform channel estimation based on theconfigured DMRS structure. The DMRS structure may be semi-statically ordynamically configured. The simplest method of semi-staticallyconfiguring the DMRS structure is to configure the DMRS structurethrough higher layer signaling. More specifically, configurationinformation may be inserted into an RS-related signaling field of RRC asshown in [Table 9] below.

TABLE 9    -- ASN1START    DMRS-PatternId ::=             INTEGER0..maxDMRS-Pattern)    DMRS-timeDensityId::=     INTEGER(0..maxDMRS-Time)    DMRS-frequencyDensityld ::=     INTEGER(0..maxDMRS-Frecteuncy)    -- ASN1STOP

Specifically, in [Table 9], mapping information can be indicated indifferent patterns through a DMRS-PatternId. A maxDMRS-Pattern indicatesa maximum number of DMRS-PatternIds which can be configured. Forexample, it is noted that mapping patterns are different in the case inwhich 12 orthogonal DMRS ports are mapped for MU-MIMO and the case inwhich 8 orthogonal DMRS ports are mapped in the embodiment. In thiscase, different pattern information may be indicated using theDMRS-PatternId. Specifically, the DMRS-PatternId is configured as (0, 1)in which case 0 may indicate a pattern that supports 8 ports for SU-MIMOand 1 may indicates a pattern that supports 12 ports for MU-MIMO. Inanother example, the DMRS-PatternId is configured as (0, 4, 8, 12) inwhich case 0 may indicate a DMRS pattern that operates in SU-MIMO, and4, 8, and 12 may indicate DMRS patterns corresponding to 4, 8, and 12used DMRS antenna ports, respectively. At this time, if theDMRS-PatternId is configured as 12, only DMRS pattern for MU-MIMO may beindicated.

Further, the extended RS structure on the time can be indicated througha DMRS-timeDensityId in [Table 9]. A maxDMRS-Time indicates a maximumnumber of DMRS-timeDensityId which can be configured. For example, themaxDMRS-Time may be used to configure the front-loaded RS and theextended RS structure on the time like the extended DMRS. Last,different RS densities on the frequency may be configured through aDMRS-frequencyDensityId in [Table 9]. A maxDMRS-Frequency indicates amaximum number of DMRS-frequencyDensityIds which can be configured. Forexample, the DMRS-frequencyDensityId may be used to configure a low RSdensity on the frequency in order to control RS overhead.

The term of a field value configured in [Table 9] may be replaced withanother term. The term is only for a specific example to easily describetechnology of the disclosure and help understanding of the disclosureand does not limit the scope of the disclosure. That is, it is apparentto those skilled in the art that the operation can be performed throughanother term based on the technical idea of the disclosure. Through themethod, the DMRS structure can be semi-statically configured through RRCand the UE can detect the structure of the currently transmitted DMRSthrough a value configured in RRC.

Next, a method by which the base station dynamically configures a DMRSstructure suitable for a transmission environment will be described. Ifinformation on the DMRS is configured through a MAC CE by a methodsimilar to the method of configuring DMRS information through RRC, theinformation on the DMRS structure may be more dynamically configured.The simplest method of dynamically configuring the DMRS structure is totransmit DCI containing information on the DMRS structure. At this time,a DCI format to which a field for dynamically operating the DMRSstructure is not applied may be separately defined for the basicoperation. If the DMRS structure is configured using DCI, there is anadvantage of dynamically changing the DMRS structure. On the other hand,there is a disadvantage of generating DCI overhead for the operation.

Accordingly, the configuration of the DMRS structure may be performed ina hierarchical configuration structure corresponding to a combination ofsemi-static signaling and dynamic signaling. Specifically, in [Table 9],the DMRS-timeDensityId and DMRS-frequencyDensityId may be configuredthrough RRC, and the DMRS-PatternId may be configured through the MAC CEor DCI. This is because there is no need to change the DMRS pattern inaccordance with a channel change on the time and frequency as rapidly asdynamic signaling is needed and thus the DMRS pattern may be configuredthrough RRC, and there is a need to dynamically operate the DMRS patternfor SU and MU and thus DMRS pattern information therefor may beconfigured through the MAC CE or DCI.

Embodiment 2-2

<Embodiment 2-2> proposes a method of effectively operating a DMRSsequence when the DMRS sequence is generated according to an increasedDMRS sequence length in the NR system. As described above, when a DMRSsequence r(m) is generated on the basis of a PN sequence C(n), agenerated sequence length may be determined by the number A of DMRS REswithin the PRB and the maximum N_(RB) ^(max) of RBs that support DL orUL of the NR system as shown in [Equation 14] below.

$\begin{matrix}{{{r(m)} = {{\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {2m} \right)}}} \right)} + {j\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {{2m} + 1} \right)}}} \right)}}},{m = 0},1,\ldots\;,{{AN}_{RB}^{\max} - 1}} & \left\lbrack {{Equation}\mspace{14mu} 14} \right\rbrack\end{matrix}$

However, various DMRS structures may be supported in the NR system, anda method of effectively generating the DMRS sequence in consideration ofvarious DMRS structures and mapping the DMRS sequence to resources isneeded. Further, the NR system supports various numerologies and alsoconsiders support of channel bandwidths up to 400 MHz. If supportedsubcarrier spacings are 15, 30, 60, 120, 240, and 480 kHz and channelbandwidths are 5, 10, 40, 80, 100, 200, and 400 MHz, the maximum numberof subcarriers and the maximum number RBs are as shown in [Table 10] and[Table 11].

TABLE 10 SCS Channel bandwidth (MHz) (kHz) 5 10 40 80 100 200 400 15 330660 2640 5280 6600 13200 26400 30 165 330 1320 2640 3300 6600 13200 6082.5 165 660 1320 1650 3300 6600 120 41.25 82.5 330 660 825 1650 3300240 20.625 41.25 165 330 412.5 825 1650 480 10.3125 20.625 82.5 165206.25 412.5 825

TABLE 11 SCS Channel bandwidth (MHz) kHz RB size 5 10 40 80 100 200 40015  180 kHz 27.5 55 220 440 550 1100 2200 30  360 kHz 13.75 27.5 110 PI275 550 1100 60  720 kHz 6.875 13.75 55 110 137.5 275 550 120 1.44 MHz3.4375 6.875 27.5 55 68.75 137.5 275 240 2.88 MHz 1.71875 3.4375 13.7527.5 34.375 68.75 137.5 480 5.76 MHz 0.859375 1.71875 6.875 13.7517.1875 34.375 68.75

The number of subcarriers and the number of RBs presented in [Table 10]and [Table 11] are merely examples, and different values may be usedaccording to progress of the NR standardization. Referring to [Table 10]and [Table 11], the maximum number of RBs supported by the NR system mayhave a different value depending on supported subcarrier spacing and achannel bandwidth, and if it is assumed that the maximum number ofsupportable subcarriers is 6600, the maximum number of RBs may increaseto 550. On the other hand, if the same channel bandwidth is used butsubcarrier spacing increases, the maximum number of supported RBsdecreases. Accordingly, a method of effectively operating the DMRSsequence length according to various numbers of supported RBs is needed.

First, a method of determining the number A of DMRS REs within the PRBwill be described with reference to [Equation 14]. Specifically, sincethe NR system supports various DMRS structures, the followingalternatives may be considered as a method of effectively generating theDMRS sequence.

-   -   Method 1: A is determined as the number of DMRS REs of a DMRS        pattern having the highest RE density including different DMRS        patterns in various DMRS structures.    -   Method 2: A is determined as the number of DMRS REs of a        front-loaded DMRS pattern in various DMRS structures.

Among the alternatives, method 1 is a method of determining A as thenumber DMRS REs of the DMRS pattern having the highest RE densityincluding different DMRS pattern in various DMRS structures andgenerating the DMRS sequence but using only a portion of the sequence inthe case of the DMRS pattern having a lower RE density. Morespecifically, in description based on reference numerals 2510, 2610,2620, and 2630 of FIGS. 25 and 26, the DMRS sequence is generated basedon the DMRS pattern having the highest RE density in method 1 asindicated by reference numeral 2630. If the DMRS pattern having the lowRE density is used as indicated by reference numerals 2510, 2610, and2620, only some of the generated patterns may be mapped to resources.

Unlike this, method 2 is a method of determining A as the number of DMRSREs of the front-loaded DMRS pattern in various DMRS structures andgenerating the DMRS sequence, but reusing and extending the generatedsequence in the case of the DMRS pattern having a higher RE density.More specifically, in description based on reference numerals 2510,2610, 2620, and 2630 of FIGS. 25 and 26, the DMRS sequence is generatedon the basis of the front-loaded DMRS pattern in method 2 as indicatedby reference numeral 2510. If the DMRS pattern having the high REdensity is used as indicated by reference numerals 2610, 2620, and 2630,the sequence of the generated front-loaded DMRS pattern may berepeatedly mapped to resources for the extended DMRS.

If all of the unit DMRS patterns having different densities on thefrequency are supported in method 2 as illustrated in FIG. 22, thesequence may be generated on the basis of the unit DMRS pattern having ahigher density. More specifically, if both reference numerals 2210 and2220 are supported, when the sequence is generated on the basis ofreference numeral 2220 and the unit DMRS pattern having the low densityis configured as indicated by reference numeral 2210, a portion of thegenerated sequence may be punctured and the remaining sequence may bemapped to resources. Compared to method 1, method 2 has an advantage ofoperating a shorter DMRS sequence.

Next, a method of determining a maximum value N_(RB) ^(max) of thenumber of RBs supported for DL or UL in [Equation 14] will be described.As described above, the maximum number of RBs supported by the NR systemvaries depending on supported subcarrier spacing and a supported channelbandwidth, and the maximum number of supportable RBs may significantlyincrease compared to the LTE system. Accordingly, a method ofeffectively operating the DMRS sequence length according to variousnumbers of supported RBs is needed. At this time, the followingalternatives may be considered as the method of determining the DMRSsequence length.

-   -   Method 1: N_(RB) ^(max) is configured in consideration of a        supportable maximum bandwidth in currently configured subcarrier        spacing.    -   Method 2: N_(RB) ^(max) is configured in consideration of all        subcarrier spacings defined in the NR system and a supportable        maximum bandwidth.

Among the alternatives, method 1 is a method of configuring N_(RB)^(max) in consideration of the supportable maximum bandwidth incurrently configured subcarrier spacing. More specifically, in [Table11], if the currently configured subcarrier spacing is 15 kHz, thenumber of RBs may be 550 in consideration of the supportable maximumbandwidth of 100 MHz. If the currently configured subcarrier spacing is15 kHz, the number of RBs may be 220 in consideration of the supportablemaximum bandwidth of 40 MHz. On the other hand, method 2 is a method ofconfiguring N_(RB) ^(max) in consideration of the supportable maximumbandwidth in all subcarrier spacings defined in the NR system, so thatN_(RB) ^(max) may be configured as 550 which is the largest number ofRBs based on [Table 11].

In order to minimize the DMRS sequence length to be generated, allsupported subcarrier spacings may be classified into <6 GHz(under 6 GHz)and >6 GHz(above 6 GHz) in method 2. Specifically, in the case of <6GHz, the supported subcarrier spacing is limited to 15, 30, and 60 kHzin which case N_(RB) ^(max) may be configured as 550 which the largestnumber of RBs based on [Table 11]. However, in the case of >6 GHz, thesupported subcarrier spacing is limited to 120, 240, and 480 kHz inwhich case N_(RB) ^(max) may be configured as 275 which the largestnumber of RBs based on [Table 11]. According to method 2, N_(RB) ^(max)may be determined in the set only in consideration of subcarrier spacingsupported by the base station and the channel bandwidth. For example, ifthe subcarrier spacing supported by the base station is limited to 15,30, and 60 kHz and the supported channel bandwidth is limited to 5, 10,and 40 MHz, N_(RB) ^(max) may be configured as 220 which is the largestnumber of RBs in the set based on [Table 11].

However, even though the alternatives are considered, the DMRS sequencelength to be generated may be still very long compared to the currentLTE system. Accordingly, in order to solve the problem, the followingmethod may be considered. The proposed method is a method of usingtwo-step resource allocation. In order to prevent an increase in the RBGsize due to an increased channel bandwidth, two-step resource allocationmay be used.

FIG. 27 illustrates an example of a two-step resource allocation method.Specifically, as illustrated in FIG. 27, if a system bandwidthcorresponding to a maximum of 500 RBs is allocated, the two-stepresource allocation method may configure a resource allocation locationof 100 RBs among the 500 RBs through a bitmap of 5 bits in a first stepand configure a resource allocation location of 4 RBs among theconfigured 100 RBs through a bitmap of 25 bits in a second step asindicated by reference numeral 2710. Accordingly, N_(RB) ^(max) mayreflect the two-step resource allocation rather than being determined onthe basis of the currently allocated maximum bandwidth. Morespecifically, if the system bandwidth corresponding to the maximum of500 RBs is allocated in reference numeral 2710, N_(RB) ^(max) is not 500but may be determined as 100 RBs which are determined in the first stepof the two-step resource allocation. The method of determining N_(RB)^(max) using the two-step resource allocation may be applied to bothmethod 1 and method 2.

Embodiment 2-3

<Embodiment 2-3> describes a method of TRP-specifically generating andinitializing the DMRS sequence in the NR system. TRP-specific generationof the $8 DMRS sequence means that every TRP has a different DMRSsequence through generation of the DMRS sequence using a TRP ID. Here, atransmission reception point (TRP) may be used to indicate a cell, and aTRP ID may be used to indicate a cell ID. In all embodiments of thedisclosure, the terms “TRP” and “cell” may be interchangeably used.TRP-specific generation of the DMRS sequence has an advantage ofrandomizing cross-correlation of the DMRS sequence between differentTRPs as much as possible. On the other hand, in order to allow the UE toeffectively remote an interference signal from another TRP, there is adisadvantage in that the UE should receive signaling of DMRS informationof another TRP such as another TRP ID. The disclosure proposes detailedmethods of TRP-specifically generating and initializing the DMRSsequence.

Specifically, <Embodiment 2-3> suggests a method of initializing theDMRS sequence with a cell ID, a slot number, and a scramblingidentifier. A first method may be expressed by the following equation.c _(init)=2^(X+Y)(n _(s)+1)+2^(X) n _(ID) ^((n) ^(SCID) ⁾ +n_(SCID)  [Equation 15]

In the equation, n_(s) denotes a slot number within a transmission frameand n_(SCID) denotes a scrambling identifier, and it is assumed that avalue of the scrambling identifier is 0 unless specifically mentioned.In the NR system, n_(SCID) may have two or more values. In n_(SCID), thenumber N of values may be configured to have two values such as 0 and 1in consideration of DMRS sequence scrambling between two TRPs in CoMPoperation like in the LTE system or configured to have two or morevalues such as i=0, 1, . . . , N in consideration of more variousoperation environments than the NR system. For example, extension of N=4may be considered. Further, X denotes the number of bits identifyingn_(SCID) and may be determined as X=log₂(N). n_(ID) ^((i)),i=0, 1, . . ., N may be determined as follows.

-   -   n_(ID) ^((i))=N_(ID) ^(cell) if no value for n_(ID) ^(DRMS,i) is        provided by higher layers or if DCI format which does not        support n_(SCID) values is used for the DCI associated with the        PDSCH transmission    -   n_(ID) ^((i))=n_(ID) ^(DRMS,i) otherwise

n_(ID) ^(DRMS,i) may be configured in a higher layer through a methodsimilar to [Table 12] below. [Table 12], N_cellID denotes the number ofcell IDs, and may be 504 in the LTE system but may be extended to 1000in the NR system. [Table 12] shows an example of the case in which thenumber of n_(SCID) is 4, and 4 n_(SCID) may be reduced to 2 n_(SCID) orfurther increased according to considerations of the NR system. In[Equation 15], Y may be the number of bits for identifying the cell ID,and if the number of cell IDs is 1000, Y=10.

   -- ASN1START    DMRS-Config ::=     CHOICE { release     NULL, setup    SEQUENCE { scramblingIdentity INTEGER (0..N_cel1ID-1),scramblingIdentity2 INTEGER (0..N_ce1lID-1), scrarnblingIdentity3INTEGER (0..N_cellID-1), scramblingIdentity4 INTEGER (0..N_cellID-1) }

Referring to [Equation 15] above, the DMRS sequence is initialized inevery slot. However, in the NR system, as subcarrier spacing is larger,a slot length significantly becomes shorter. More specifically, the slotlength according to the subcarrier spacing (SCS) is as shown in [Table13] below.

TABLE 13 OFDM symbol number within slot SCS (kHz) 7 14 15  0.5 ms 1 ms30 0.25 ms 0.5 ms 60 0.125 ms  0.25 ms 120 — 0.125 ms 240 — 0.0625 ms480 — 0.03125 ms

As shown in [Table 13] above, if as the subcarrier spacing is larger,the slot length significantly becomes shorter, initialization of theDMRS sequence in every slot may be a burden to implementation.Accordingly, in order to solve the problem, a modified equation isproposed below.c _(init)=2^(X+Y)(└n _(s) /M┘+1)+2^(X) n _(ID) ^((n) ^(SCID) ⁾ +n_(SCID)  [Equation 16]

In the equation, description of all parameters except for M is the sameas that of [Equation 15]. In the equation, M is a parameter forcontrolling initialization of the DMRS sequence depending on the slotlength, and a value of M for DMRS sequence initialization based on aslot length of 1 ms may be as shown in [Table 14] below. A method ofvarying DMRS sequence initialization depending on the slot length in[Equation 16] may be expressed by another method. For example, accordingto the use of [Equation 15], the following phrase may be used.

The UE is not expected to update c_(init) less than X msec.

Here, X=1 msec.

TABLE 14 OFDM symbol number within slot SCS (kHz) 7 14 15 2 1 30 4 2 608 4 120 — 8 240 — 16 480 — 32

Another method TRP-specifically generating and initializing the DMRSsequence may be expressed by [Equation 17] below. The following methodis a method of further randomizing the cross-correlation of the DMRSsequence between different TRPs than the method of [Equation 15].Specifically, it is assumed that

and

are PN sequences generated on the basis of initialization values ofX₁=first cell ID and X₂=second cell ID and that

and

are PN sequences generated on the basis of initialization values of X₁+Zand X₂+Z. It is assumed that Z is a slot number. At this time, based onthe assumption of a time synchronized network, the cross-correlationbetween

and

is the same as the cross-correlation between

and

. This means that

and

have the bad cross-correlation therebetween if

and

have the bad cross-correlation therebetween. Accordingly, in order tosolve the problem, a modified equation is proposed below.c _(init)=2^(X+Y)(n _(s)+1)·(2n _(ID) ^((n) ^(SCID) ⁾+2^(X) n _(ID)^((n) ^(SCID) ⁾ +n _(SCID)  [Equation 17]

In the above equation, description of all parameters except for (2n_(ID)^((n) ^(SCID) ⁾+1) is the same as that of [Equation 15]. In the aboveequation, (2n_(ID) ^((n) ^(SCID) ⁾+1) may be replaced with (n_(ID) ^((n)^(SCID) ⁾+1). In the above equation, (2n_(ID) ^((n) ^(SCID) ⁾+1), thereason to use (2n_(ID) ^((n) ^(SCID) ⁾+1) is that using (2n_(ID) ^((n)^(SCID) ⁾+1) can further randomize the cross-correlation of the DMRSsequence between different TRPs than using (n_(ID) ^((n) ^(SCID) ⁾+1).More specifically, when it is assumed that M1 and M2 are different cellIDs, the case in which M2+1=2(M1+1) is considered. For example, the casecorresponds to (0,1), (1,3), (2,5), (3,7), . . . . In this case, if thesequence is initialized using (n_(ID) ^((n) ^(SCID) ⁾+1), thecross-correlation between an I component corresponding to the cell ID Mand a Q component corresponding to the cell ID M2 in [Equation 14] doesnot vary depending on the slot number. In this case, the above problemmay be solved using (2n_(ID) ^((n) ^(SCID) ⁾+1).

Referring to [Equation 17] above, the DMRS sequence is initialized inevery slot. However, in the NR system, as subcarrier spacing is larger,the slot length significantly becomes shorter. As shown in [Table 13]above, if as the subcarrier spacing is larger, the slot lengthsignificantly becomes shorter, initialization of the DMRS sequence inevery slot may be a burden to implementation. Accordingly, in order tosolve the problem, a modified equation is proposed below.c _(init)=2^(X+Y)(└n _(s) /M┘+1)·(2n _(ID) ^((n) ^(SCID) ⁾+1)+2^(X) n_(ID) ^((n) ^(SCID) ⁾ +n _(SCID)  [Equation 18]

In the equation, description of all parameters except for M is the sameas that of [Equation 17]. In the equation, M is a parameter forcontrolling initialization of the DMRS sequence depending on the slotlength, and a value of M for DMRS sequence initialization based on aslot length of 1 ms may be as shown in [Table 14] above. A method ofvarying DMRS sequence initialization depending on the slot length in[Equation 18] may be expressed by another method. For example, accordingto the use of [Equation 17], the following phrase may be used.

The UE is not expected to update c_(init) less than X msec.

Here, X=1 msec.

Another method TRP-specifically generating and initializing the DMRSsequence may be expressed by [Equation 19] below. The following methodis a modified method of [Equation 17] and is to avoid repeatedly usingn_(ID) ^((n) ^(SCID) ⁾ in [Equation 17]. To this end, the followingequation may be used.c _(init)=2^(X)(n _(s)+1)·(2n _(ID) ^((n) ^(SCID) ⁾+1)+n_(SCID)  [Equation 19]

Description of all parameters in the equation is the same as that of[Equation 15]. However, in the NR system, as subcarrier spacing islarger, a slot length significantly becomes shorter. As shown in [Table13] above, if as the subcarrier spacing is larger, the slot lengthbecomes shorter, initialization of the DMRS sequence in every slot maybe a burden to implementation. Accordingly, in order to solve theproblem, a modified equation is proposed below.c _(init)=2^(X)(└n _(s) /M┘)·(2n _(ID) ^((n) ^(SCID) ⁾+1)+n_(SCID)  [Equation 20]

In the equation, description of all parameters except for M is the sameas that of [Equation 19]. In the equation, M is a parameter forcontrolling initialization of the DMRS sequence depending on the slotlength, and a value of M for DMRS sequence initialization based on aslot length of 1 ms may be as shown in [Table 14] above. A method ofvarying DMRS sequence initialization depending on the slot length in[Equation 20] may be expressed by another method. For example, accordingto the use of [Equation 19], the following phrase may be used.

The UE is not expected to update c_(init) less than X msec.

Here, X=1 msec.

Embodiment 2-4

<Embodiment 2-4> describes a method of resource-specifically generatingand initializing the DMRS sequence in the NR system. If the DMRSsequence is resource-specifically generated, every TRP has the same DMRSsequence since the DMRS sequence is not generated using a TRP ID unlikein <Embodiment 2-3>. The DMRS sequence has different sequences inallocated resource regions. Accordingly, the method has a disadvantageof increasing the cross-correlation of the DMRS sequence betweendifferent TRPs. However, the method has an advantage in that the UE doesnot need to receive signaling of DMRS information of another TRP such asanother TRP ID in order to allow the UE to effectively remote aninterference signal from another TRP.

The disclosure proposes detailed methods of resource-specificallygenerating and initializing the DMRS sequence. More specifically,<Embodiment 2-4> suggests a method of initializing the DMRS sequencewith a slot number and a scrambling identifier. A first method may beexpressed by [Equation 21] below.c _(init)=2^(X)(n _(s)+1)+n _(SCID)  [Equation 21]

In the equation, n, denotes a slot number within a transmission frameand n_(SCID) denotes a scrambling identifier, and it is assumed that avalue of the scrambling identifier is 0 unless specifically mentioned.In the NR system, n_(SCID) may have two or more values. In n_(SCID), thenumber N of values may be configured to have two values such as 0 and 1in consideration of DMRS sequence scrambling between two TRPs in CoMPoperation like in the LTE system or configured to have two or morevalues such as i=0, 1, . . . , N in consideration of more variousoperation environments than the NR system. For example, extension of N=4may be considered. Further, X denotes the number of bits identifyingn_(SCID) and may be determined as X=log₂(N).

Referring to [Equation 21] above, the DMRS sequence is initialized inevery slot. However, in the NR system, as subcarrier spacing is larger,a slot length significantly becomes shorter. As shown in [Table 13]above, if as the subcarrier spacing is larger, the slot length becomesshorter, initialization of the DMRS sequence in every slot may be aburden to implementation. Accordingly, in order to solve the problem, amodified equation is proposed below.c _(init)=2^(X)(└n _(s) /M┘+1)+n _(SCID)  [Equation 22]

In the above equation, description of all parameters except for M is thesame as that of [Equation 21]. In the equation, M is a parameter forcontrolling initialization of the DMRS sequence depending on the slotlength, and a value of M for DMRS sequence initialization based on aslot length of 1 ms may be as shown in [Table 14] above. A method ofvarying DMRS sequence initialization depending on the slot length in[Equation 22] may be expressed by another method. For example, accordingto the use of [Equation 21], the following phrase may be used.

The UE is not expected to update Ca less than X msec.

Here, X=1 msec.

Another method resource-specifically generating and initializing theDMRS sequence may be expressed by [Equation 23] below. The followingmethod is a method of further randomizing the cross-correlation of theDMRS sequence between different TRPs than the method of [Equation 2m].Specifically, if it is assumed that

and

are PN sequences generated on the basis of initialization values ofX₁=first cell ID and X₂=second cell ID and that

and

are PN sequences generated on the basis of initialization values of X₁+Zand X₂+Z. It is assumed that Z is a slot number. At this time, based onthe assumption of a time synchronized network, the cross-correlationbetween

and

is the same as the cross-correlation between

and

. This means that

and

has the bad cross-correlation therebetween if

and

has the bad cross-correlation therebetween. Accordingly, in order tosolve the problem, a modified equation is proposed below.c _(init)=2^(X)(n _(s)+1)·(2n _(SCID)+1)+n _(SCID)  [Equation 23]

In the above equation, description of all parameters except for(2n_(SCID)+1) is the same as that of [Equation 21]. In the aboveequation, (2n_(SCID)+1) may be replaced with (n_(SCID)+1). In the aboveequation, the reason to use (2n_(SCID)+11) is that using (2n_(SCID)+1)can further randomize the cross-correlation of the DMRS sequence betweendifferent TRPs than using (n_(SCID)+1). More specifically, when it isassumed that M1 and M2 are different scrambling identifiers, the case inwhich M2+1=2(M1+1) is considered. For example, the case corresponds to(0,1), (1,3), (2,5), (3,7), . . . . In this case, if the sequence isinitialized using (n_(SCID)+1), the cross-correlation between an Icomponent corresponding to the cell ID M1 and a Q componentcorresponding to the cell ID M2 in [Equation 14] does not vary dependingon the slot number. In this case, the above problem may be solved using(2n_(SCID)+1).

If [Equation 23] is applied, the DMRS sequence is initialized in everyslot. However, in the NR system, as subcarrier spacing is larger, a slotlength significantly becomes shorter. As shown in [Table 13] above, ifas the subcarrier spacing is larger, the slot length becomes shorter,initialization of the DMRS sequence in every slot may be a burden toimplementation. Accordingly, in order to solve the problem, a modifiedequation is proposed below.c _(init)=2^(X)(└n _(s) /M┘+1)·(2n _(SCID)+1)+n _(SCID)  [Equation 24]

In the above equation, description of all parameters except for M is thesame as that of [Equation 23]. In the equation, M is a parameter forcontrolling initialization of the DMRS sequence depending on the slotlength, and a value of M for DMRS sequence initialization based on aslot length of 1 ms may be as shown in [Table 14] above. A method ofvarying DMRS sequence initialization depending on the slot length in[Equation 24] may be expressed by another method. For example, accordingto the use of [Equation 23], the following phrase may be used.

The UE is not expected to update c_(init) less than X msec.

Here, X=1 msec.

Embodiment 2-5

<Embodiment 2-5> proposes a detailed method of mapping antenna ports onthe basis of the front-loaded DMRS pattern based on current agreement of3GPP. The front-loaded DMRS pattern agreed by 3GPP may be divided intotype 1 and type 2, which may be configured through higher layersignaling. The DMRS density may vary depending on the method of mappingantenna ports, which results in channel estimation performance, and thusan optimized mapping method according to each type is very important toDMRS design. If an additional DMRS is transmitted in the transmissionslot, a DMRS pattern which is the same as the following DMRS pattern maybe repeated after the front-loaded DMRS.

-   -   Configuration type 1    -   One symbol: Comb 2+2 CS, up to 4 ports    -   Two symbols: Comb 2+2 CS+TD-OCC ({1 1} and {1−1}), up to 8 ports    -   Note: It should be possible to schedule up to 4 ports without        using both {1,1} and {1,−1}.    -   Configuration type 2    -   One symbol: 2-FD-OCC across adjacent REs in the frequency        domain, up to 6 ports    -   Two symbols: 2-FD-OCC across adjacent REs in the frequency        domain+TD-OCC (both {1,1} and {1,−1}) up to 12 ports    -   Note: It should be possible to schedule up to 6 ports without        using both {1,1} and {1,−1}.

FIGS. 28 and 29 illustrate in detail patterns varying depending on anantenna port mapping method based on the agreement. In the followingembodiment, an antenna port p is expressed as p=P1 to P8 in type 1 andexpressed as p v: P1 to P12 in type 2. However, the port number may bedisplayed differently. For example, p=1000 to 1007 in type 1 and p=1000to 1011 in type 2.

First, in the case of a type 1 pattern, comb 2 and 2 CS are the basicstructure like the agreement, and in the case of the two-symbol pattern,TD-OCC({1 1} and {1−1}) is applied and a maximum of 8 orthogonal DMRSports are supported. As described above, a method of supporting aplurality of antenna ports is applied and the DMRS may be mapped to afirst OFDM symbol and a k^(th) subcarrier on the time as shown in thefollowing equation.a _(k,l) ^((p,μ)) =e ^(jφ) ^(k) ·w _(t)(l′)·r(m+m ₀)k=k ₀+2m+Δl=l ₀ +l′  [Equation 25]

In [Equation 25], r(m) denotes the DMRS sequence generated in [Equation14] of <Embodiment 2-2>, w_(t)(l′) denotes application of a TD-OCCapplied to the two-symbol pattern, and φ_(k) denotes a phase forapplication of 2 CS. The values varying depending on the antenna portmethod is described in detail in the following table.

FIG. 28 illustrates an example of a pattern available in type 1according to the antenna port mapping method. Reference numerals 2800and 2802 indicate antenna ports which can be mapped to differentfrequency locations. Reference numerals 2810 and 2820 indicate examplesin which the DMRS according to type 1 is mapped to one symbol. Referencenumeral 2810 corresponds to a mapping method according to a method bywhich DMRS ports P1/P3 and P2/P4 are separated by comb 2, and referencenumeral 2820 corresponds to a mapping method according to a method bywhich DRMS ports P1/P2 and P3/P4 are separated by comb 2. In referencenumerals 2810 and 2820, a maximum of two ports can be separated using 2CS within the same comb. Specifically, the mapping method 2810 may havethe following DMRS density.

-   -   In the case in which 6 REs are used <=one layer transmission    -   In the case in which 12 REs are used > one layer transmission        Unlike the above, the mapping method 2820 may have the following        DMRS density.    -   In the case in which 6 REs are used <=two layer transmission    -   In the case in which 12 REs are used > two layer transmission

Accordingly, the methods 2810 and 2820 may have different DMRS densitiesdepending on the number of transmitted DMRS ports.

Subsequently, reference numerals 2830 to 2870 illustrate examples ofmapping type 1 to two symbols. Reference numeral 2830 corresponds to amapping method according to a method by which DMRS ports P1/P3/P5/P7 andP2/P4/P6/P8 are separated by comb 2, and reference numeral 2840corresponds to a mapping method according to a method by which DRMSports P1/P3/P5/P6 and P2/P4/P7/P8 are separated by comb 2. Referencenumeral 2850 corresponds to a mapping method according to a method bywhich DMRS ports P1/P2/P5/P7 and P3/P4/P6/P8 are separated by comb 2,and reference numeral 2860 corresponds to a mapping method according toa method by which DRMS ports P1/P2/P5/P6 and P3/P4/P7/P8 are separatedby comb 2. Last, reference numeral 2870 corresponds to a mapping methodaccording to a method by which DMRS ports P1/P2/P3/P4 and P5/P6/P7/P8are separated by comb 2. In reference numerals 2830 to 2870, a maximumof four ports may be separated using 2 CS and TD-OCC within the samecomb.

Specifically, the mapping methods 2830 and 2840 may have the followingDMRS density.

-   -   In the case in which 12 REs are used <=one layer transmission    -   In the case in which 24 REs are used > one layer transmission        Unlike the above, the mapping methods 2850 and 2860 may have the        following DMRS density.    -   In the case in which 12 REs are used <=: two layer transmission    -   In the case in which 24 REs are used > two layer transmission        Unlike the above, the mapping method 2870 may have the following        DMRS density.    -   In the case in which 12 REs are used <=four layer transmission    -   In the case in which 24 REs are used > four layer transmission        According to the antenna port mapping method of type 1, it is        noted that the DMRS density varies depending thereon and the        one-symbol pattern and the two-symbol pattern for the DMRS may        use different mapping patterns depending on the optimized        mapping method.

More specifically, a detailed method of configuring parameters in[Equation 25] varying depending on which antenna port mapping method isused by the one-symbol pattern or the two-symbol pattern for the DMRS ispresented. First, available configuration methods of the one-symbolpattern and the two-symbol pattern for the DMRS may be divided into 10methods according to the antenna port mapping method illustrated in FIG.28, and configuration of parameters in [Equation 25] is describedthrough a table.

-   -   Case1: One symbol 2810 and Two symbol 2830    -   Case2: One symbol 2810 and Two symbol 2840    -   Case3: One symbol 2810 and Two symbol 2850    -   Case4: One symbol 2810 and Two symbol 2860    -   Case5: One symbol 2810 and Two symbol 2870    -   Case6: One symbol 2820 and Two symbol 2830    -   Case7: One symbol 2820 and Two symbol 2840    -   Case8: One symbol 2820 and Two symbol 2850    -   Case9: One symbol 2820 and Two symbol 2860    -   Case10: One symbol 2820 and Two symbol 2870

In the case of the two-symbol pattern, additional cases according topriorities of 2 CS and TD-OCC applied to antenna ports within the combmay be considered.

-   -   Method 1: first apply 2 CS and then apply TD-OCC in two-symbol        pattern    -   Method 2: first apply TD-OCC and then apply 2 CS in two-symbol        pattern

[Table 15-1] and [Table 15-2] below show configuration values ofparameters in [Equation 25] according to case 1. [Table 15-1] showsparameters configured through a method (case 1-1) of first applying 2 CSand then applying TD-OCC in the two-symbol pattern.

TABLE 15-1 Antenna port w_(t)(l′) = [w_(t)(0) w_(t)(1)] p Δ φ_(k) Onesymbol Two symbol P1 0 0 [+1] [+1 +1] P2 1 0 [+1] [+1 +1] P3 0 π(└k/2┘)[+1] [+1 +1] P4 1 π(└k/2┘) [+1] [+1 +1] P5 0 0 — [+1 −1] P6 1 0 — [+1−1] P7 0 π(└k/2┘) — [+1 −1] P8 1 π(└k/2┘) — [+1 −1]

[Table 15-2] shows parameters configured through a method (case 1-2) offirst applying TD-OCC and then applying 2 CS in the two-symbol pattern.In [Table 15-2], Two symbol(*) considers the case in which one-symbolpattern is repeated and a maximum of 4 ports are scheduled in twosymbols, which is a method of considering that it is difficult to applyTD-OCC to the high frequency band.

TABLE 15-2 Δ φ_(k) Δ φ_(k) Δ φ_(k) w_(t)(l′) = [w_(t)(0) w_(t)(1)]Antenna One Two Two One Two Two port^(p) symbol symbol symbol (*) symbolsymbol symbol (*) P1 0 0 0 0 0 0 [+1] [+1 +1] [+1 +1] P2 1 0 1 0 1 0[+1] [+1 +1] [+1 +1] P3 0 π(└k/2┘) 0 0 0 π(└k/2┘) [+1] [+1 −1] [+1 +1]P4 1 π(└k/2┘) 1 0 1 π(└k/2┘) [+1] [+1 −1] [+1 +1] P5 — — 0 π(└k/2┘) — —— [+1 +1] — P6 — — 1 π(└k/2┘) — — — [+1 +1] — P7 — — 0 π(└k/2┘) — — —[+1 −1] — P8 — — 1 π(└k/2┘) — — — [+1 −1] —

[Table 16-1] and [Table 16-2] below show configuration values ofparameters in [Equation 25] according to case 2. [Table 16-1] showsparameters configured through a method (case 2-1) of first applying 2 CSand then applying TD-OCC in the two-symbol pattern.

TABLE 16-1 Antenna port w_(t)(l′) = [w_(t)(0) w_(t)(1)] p Δ φ_(k) Onesymbol Two symbol P1 0 0 [+1] [+1 +1] P2 1 0 [+1] [+1 +1] P3 0 π(└k/2┘)[+1] [+1 +1] P4 1 π(└k/2┘) [+1] [+1 +1] P5 0 0 — [+1 −1] P6 0 π(└k/2┘) —[+1 −1] P7 1 0 — [+1 −1] P8 1 π(└k/2┘) — [+1 −1]

[Table 16-2] shows parameters configured through a method (case 2-2) offirst applying TD-OCC and then applying 2 CS in the two-symbol pattern.In [Table 16-2], Two symbol(*) considers the case in which one-symbolpattern is repeated and a maximum of 4 ports are scheduled in twosymbols, which is a method of considering that it is difficult to applyTD-OCC to the high frequency band.

TABLE 16-2 Δ φ_(k) Δ φ_(k) Δ φ_(k) w_(t)(l′) = [w_(t)(0) w_(t)(1)]Antenna One Two Two One Two Two port^(p) One symbol Two symbol symbol(*) symbol symbol symbol (*) P1 0 0 0 0 0 0 [+1] [+1 +1] [+1 +1] P2 1 01 0 1 0 [+1] [+1 +1] [+1 +1] P3 0 π(└k/2┘) 0 0 0 π(└k/2┘) [+1] [+1 −1][+1 +1] P4 1 π(└k/2┘) 1 0 1 π(└k/2┘) [+1] [+1 −1] [+1 +1] P5 — — 0π(└k/2┘) — — — [+1 +1] — P6 — — 0 π(└k/2┘) — — — [+1 +1] — P7 — — 1π(└k/2┘) — — — [+1 −1] — P8 — — 1 π(└k/2┘) — — — [+1 −1] —

[Table 17-1] and [Table 17-2] show configuration values of parameters in[Equation 25] according to case 3. [Table 17-1] shows parametersconfigured through a method (case 3-1) of first applying 2 CS and thenapplying TD-OCC in the two-symbol pattern.

TABLE 17-1 w_(t)(l′) = [w_(t)(0) w_(t)(1)] Antenna Δ φ_(k) Δ φ_(k) OneTwo port^(p) One symbol Two symbol symbol symbol P1 0 0 0 0 [+1] [+1 +1]P2 1 0 0 π(└k/2┘) [+1] [+1 +1] P3 0 π(└k/2┘) 1 0 [+1] [+1 +1] P4 1π(└k/2┘) 1 π(└k/2┘) [+1] [+1 +1] P5 — — 0 0 — [+1 −1] P6 — — 1 0 — [+1−1] P7 — — 0 π(└k/2┘) — [+1 −1] P8 — — 1 π(└k/2┘) — [+1 −1]

[Table 17-2] shows parameters configured through a method (case 3-2) offirst applying TD-OCC and then applying 2 CS in the two-symbol pattern.In [Table 17-2], Two symbol(*) considers the case in which one-symbolpattern is repeated and a maximum of 4 ports are scheduled in twosymbols, which is a method of considering that it is difficult to applyTD-OCC to the high frequency band.

TABLE 17-2 Δ φ_(k) Δ φ_(k) Δ φ_(k) w_(t)(l′) = [w_(t)(0) w_(t)(1)]Antenna One Two Two One Two Two port p symbol symbol symbol(*) symbolsymbol symbol(*) P1 0 0 0 0 0 0 [+1] [+1 +1] [+1 +1] P2 1 0 0 0 1 0 [+1][+1 +1] [+1 +1] P3 0 π(└k/2┘) 1 0 0 π(└k/2┘) [+1] [+1 −1] [+1 +1] P4 1π(└k/2┘) 1 0 1 π(└k/2┘) [+1] [+1 −1] [+1 +1] P5 — — 0 π(└k/2┘) — — — [+1+1] — P6 — — 1 π(└k/2┘) — — — [+1 +1] — P7 — — 0 π(└k/2┘) — — — [+1 −1]— P8 — — 1 π(└k/2┘) — — — [+1 −1] —

[Table 18-1] and [Table 18-2] below show configuration values ofparameters in [Equation 25] according to case 4. [Table 18-1] showsparameters configured through a method (case 4-1) of first applying 2 CSand then applying TD-OCC in the two-symbol pattern.

TABLE 18-1 w_(t)(l′) = [w_(t)(0) w_(t)(1)] Antenna Δ φ_(k) Δ φ_(k) OneTwo port p One symbol Two symbol symbol symbol P1 0 0 0 0 [+1] [+1 +1]P2 1 0 0 π(└k/2┘) [+1] [+1 +1] P3 0 π(└k/2┘) 1 0 [+1] [+1 +1] P4 1π(└k/2┘) 1 π(└k/2┘) [+1] [+1 +1] P5 — — 0 0 — [+1 −1] P6 — — 0 π(└k/2┘)— [+1 −1] P7 — — 1 0 — [+1 −1] P8 — — 1 π(└k/2┘) — [+1 −1]

[Table 18-2] shows parameters configured through a method (case 4-2) offirst applying TD-OCC and then applying 2 CS in the two-symbol pattern.In [Table 18-2], Two symbol(*) considers the case in which one-symbolpattern is repeated and a maximum of 4 ports are scheduled in twosymbols, which is a method of considering that it is difficult to applyTD-OCC to the high frequency band.

TABLE 18-2 Δ φ_(k) Δ φ_(k) w_(t)(l′) = [w_(t)(0) w_(t)(1)] Antenna Δφ_(k) Two Two One Two Two port p One symbol symbol symbol(*) symbolsymbol symbol(*) P1 0 0 0 0 0 0 [+1] [+1 +1] [+1 +1] P2 1 0 0 0 1 0 [+1][+1 +1] [+1 +1] P3 0 π(└k/2┘) 1 0 0 π(└k/2┘) [+1] [+1 −1] [+1 +1] P4 1π(└k/2┘) 1 0 1 π(└k/2┘) [+1] [+1 −1] [+1 +1] P5 — — 0 π(└k/2┘) — — — [+1+1] — P6 — — 0 π(└k/2┘) — — — [+1 +1] — P7 — — 1 π(└k/2┘) — — — [+1 −1]— P8 — — 1 π(└k/2┘) — — — [+1 −1] —

[Table 19-1] and [Table 19-2] show configuration values of parameters in[Equation 25] according to case 5. [Table 19-1] shows parametersconfigured through a method (case 5-1) of first applying 2 CS and thenapplying TD-OCC in the two-symbol pattern.

TABLE 19-1 w_(t)(l′) = [w_(t)(0) w_(t)(1)] Antenna Δ φ_(k) Δ φ_(k) OneTwo port p One symbol Two symbol symbol symbol P1 0 0 0 0 [+1] [+1 +1]P2 1 0 0 π(└k/2┘) [+1] [+1 +1] P3 0 π(└k/2┘) 0 0 [+1] [+1 −1] P4 1π(└k/2┘) 0 π(└k/2┘) [+1] [+1 −1] P5 — — 1 0 — [+1 +1] P6 — — 1 π(└k/2┘)— [+1 +1] P7 — — 1 0 — [+1 −1] P8 — — 1 π(└k/2┘) — [+1 −1]

[Table 19-2] shows parameters configured through a method (case 5-2) offirst applying TD-OCC and then applying 2 CS in the two-symbol pattern.In [Table 19-2], Two symbol(*) considers the case in which one-symbolpattern is repeated and a maximum of 4 ports are scheduled in twosymbols, which is a method of considering that it is difficult to applyTD-OCC to the high frequency band.

TABLE 19-2 Δ φ_(k) Δ φ_(k) Δ φ_(k) w_(t)(l′) = [w_(t)(0) w_(t)(1)]Antenna One Two Two One Two Two port p symbol symbol symbol(*) symbolsymbol symbol(*) P1 0 0 0 0 0 0 [+1] [+1 +1] [+1 +1] P2 1 0 0 0 1 0 [+1][+1 −1] [+1 +1] P3 0 π(└k/2┘) 0 π(└k/2┘) 0 π(└k/2┘) [+1] [+1 +1] [+1 +1]P4 1 π(└k/2┘) 0 π(└k/2┘) 1 π(└k/2┘) [+1] [+1 −1] [+1 +1] P5 — — 1 0 — —— [+1 +1] — P6 — — 1 0 — — — [+1 −1] — P7 — — 1 π(└k/2┘) — — — [+1 +1] —P8 — — 1 π(└k/2┘) — — — [+1 −1] —

[Table 20-1] and [Table 20-2] below show configuration values ofparameters in [Equation 25] according to case 6. [Table 20-1] showsparameters configured through a method (case 6-1) of first applying 2 CSand then applying TD-OCC in the two-symbol pattern.

TABLE 20-1 w_(t)(l′) = [w_(t)(0) w_(t)(1)] Antenna Δ φ_(k) Δ φ_(k) OneTwo port p One symbol Two symbol symbol symbol P1 0 0 0 0 [+1] [+1 +1]P2 0 π(└k/2┘) 1 0 [+1] [+1 +1] P3 1 0 0 π(└k/2┘) [+1] [+1 +1] P4 1π(└k/2┘) 1 π(└k/2┘) [+1] [+1 +1] P5 — — 0 0 — [+1 −1] P6 — — 1 0 — [+1−1] P7 — — 0 π(└k/2┘) — [+1 −1] P8 — — 1 π(└k/2┘) — [+1 −1]

[Table 20-2] shows parameters configured through a method (case 6-2) offirst applying TD-OCC and then applying 2 CS in the two-symbol pattern.In [Table 20-2], Two symbol(*) considers the case in which one-symbolpattern is repeated and a maximum of 4 ports are scheduled in twosymbols, which is a method of considering that it is difficult to applyTD-OCC to the high frequency band.

TABLE 20-2 w_(t)(l′) = [w_(t)(0) w_(t)(1)] Antenna Δ φ_(k) Δ φ_(k) Δφ_(k) One Two Two port p One symbol Two symbol Two symbol(*) symbolsymbol symbol(*) P1 0 0 0 0 0 0 [+1] [+1 +1] [+1 +1] P2 0 π(└k/2┘) 1 0 0π(└k/2┘) [+1] [+1 −1] [+1 +1] P3 1 0 0 0 1 0 [+1] [+1 +1] [+1 +1] P4 1π(└k/2┘) 1 0 1 π(└k/2┘) [+1] [+1 −1] [+1 +1] P5 — — 0 π(└k/2┘) — — — [+1+1] — P6 — — 1 π(└k/2┘) — — — [+1 −1] — P7 — — 0 π(└k/2┘) — — — [+1 +1]— P8 — — 1 π(└k/2┘) — — — [+1 −1] —

[Table 21-1] and [Table 21-2] below show configuration values ofparameters in [Equation 25] according to case 7. [Table 21-1] showsparameters configured through a method (case 7-1) of first applying 2 CSand then applying TD-OCC in the two-symbol pattern.

TABLE 21-1 Antenna Δ φ_(k) Δ φ_(k) w_(t)(l′) = [w_(t)(0) w_(t)(1)] portp One symbol Two symbol One symbol Two symbol P1 0 0 0 0 [+1] [+1 +1] P20 π(└k/2┘) 1 0 [+1] [+1 +1] P3 1 0 0 π(└k/2┘) [+1] [+1 +1] P4 1 π(└k/2┘)1 π(└k/2┘) [+1] [+1 +1] P5 — — 0 0 — [+1 −1] P6 — — 0 π(└k/2┘) — [+1 −1]P7 — — 1 0 — [+1 −1] P8 — — 1 π(└k/2┘) — [+1 −1]

[Table 21-2] shows parameters configured through a method (case 7-2) offirst applying TD-OCC and then applying 2 CS in the two-symbol pattern.In [Table 21-2], Two symbol(*) considers the case in which one-symbolpattern is repeated and a maximum of 4 ports are scheduled in twosymbols, which is a method of considering that it is difficult to applyTD-OCC to the high frequency band.

TABLE 21-2 w_(t)(l′) = [w_(t)(0) w_(t)(1)] Antenna Δ φ_(k) Δ φ_(k) Δφ_(k) One Two Two port p One symbol Two symbol Two symbol(*) symbolsymbol symbol(*) P1 0 0 0 0 0 0 [+1] [+1 +1] [+1 +1] P2 0 π(└k/2┘) 1 0 0π(└k/2┘) [+1] [+1 −1] [+1 +1] P3 1 0 0 0 1 0 [+1] [+1 +1] [+1 +1] P4 1π(└k/2┘) 1 0 1 π(└k/2┘) [+1] [+1 −1] [+1 +1] P5 — — 0 π(└k/2┘) — — — [+1+1] — P6 — — 0 π(└k/2┘) — — — [+1 −1] — P7 — — 1 π(└k/2┘) — — — [+1 +1]— P8 — — 1 π(└k/2┘) — — — [+1 −1] —

[Table 22-1] and [Table 22-2] below show configuration values ofparameters in [Equation 25] according to case 8. [Table 22-1] showsparameters configured through a method (case 8-1) of first applying 2 CSand then applying TD-OCC in the two-symbol pattern.

TABLE 22-1 Antenna port w_(t)(l′) = [w_(t)(0) w_(t)(1)] p Δ φ_(k) Onesymbol Two symbol P1 0 0 [+1] [+1 +1] P2 0 π(└k/2┘) [+1] [+1 +1] P3 1 0[+1] [+1 +1] P4 1 π(└k/2┘) [+1] [+1 +1] P5 0 0 — [+1 −1] P6 1 0 — [+1−1] P7 0 π(└k/2┘) — [+1 −1] P8 1 π(└k/2┘) — [+1 −1]

[Table 22-2] shows parameters configured through a method (case 8-2) offirst applying TD-OCC and then applying 2 CS in the two-symbol pattern.In [Table 22-2], Two symbol(*) considers the case in which one-symbolpattern is repeated and a maximum of 4 ports are scheduled in twosymbols, which is a method of considering that it is difficult to applyTD-OCC to the high frequency band.

[

22-2] w_(t)(l′) = [w_(t)(0) w_(t)(1)] Antenna Δ φ_(k) Δ φ_(k) Δ φ_(k)One Two Two port p One symbol Two symbol Two symbol(*) symbol symbolsymbol(*) P1 0 0 0 0 0 0 [+1] [+1 +1] [+1 +1] P2 0 π(└k/2┘) 0 0 0π(└k/2┘) [+1] [+1 +1] [+1 +1] P3 1 0 1 0 1 0 [+1] [+1 −1] [+1 +1] P4 1π(└k/2┘) 1 0 1 π(└k/2┘) [+1] [+1 −1] [+1 +1] P5 — — 0 π(└k/2┘) — — — [+1+1] — P6 — — 1 π(└k/2┘) — — — [+1 +1] — P7 — — 0 π(└k/2┘) — — — [+1 −1]— P8 — — 1 π(└k/2┘) — — — [+1 −1] —

[Table 23-1] and [Table 23-2] below show configuration values ofparameters in [Equation 25] according to case 9. [Table 23-1] showsparameters configured through a method (case 9-1) of first applying 2 CSand then applying TD-OCC in the two-symbol pattern.

TABLE 23-1 Antenna port w_(t)(l′) = [w_(t)(0) w_(t)(1)] p Δ φ_(k) Onesymbol Two symbol P1 0 0 [+1] [+1 +1] P2 0 π(└k/2┘) [+1] [+1 +1] P3 1 0[+1] [+1 +1] P4 1 π(└k/2┘) [+1] [+1 +1] P5 0 0 — [+1 −1] P6 0 π(└k/2┘) —[+1 −1] P7 1 0 — [+1 −1] P8 1 π(└k/2┘) — [+1 −1]

[Table 23-2] shows parameters configured through a method (case 9-2) offirst applying TD-OCC and then applying 2 CS in the two-symbol pattern.In [Table 23-2], Two symbol(*) considers the case in which one-symbolpattern is repeated and a maximum of 4 ports are scheduled in twosymbols, which is a method of considering that it is difficult to applyTD-OCC to the high frequency band.

TABLE 23-2 w_(t)(l′) = [w_(t)(0) w_(t)(1)] Antenna Δ φ_(k) Δ φ_(k) Δφ_(k) One Two Two port p One symbol Two symbol Two symbol(*) symbolsymbol symbol(*) P1 0 0 0 0 0 0 [+1] [+1 +1] [+1 +1] P2 0 π(└k/2┘) 0 0 10 [+1] [+1 +1] [+1 +1] P3 1 0 1 0 0 π(└k/2┘) [+1] [+1 −1] [+1 +1] P4 1π(└k/2┘) 1 0 1 π(└k/2┘) [+1] [+1 −1] [+1 +1] P5 — — 0 π(└k/2┘) — — — [+1+1] — P6 — — 1 π(└k/2┘) — — — [+1 +1] — P7 — — 0 π(└k/2┘) — — — [+1 −1]— P8 — — 1 π(└k/2┘) — — — [+1 −1] —

[Table 24-1] and [Table 24-2] below show configuration values ofparameters in [Equation 25] according to case 10. [Table 24-1] showsparameters configured through a method (case 10-1) of first applying 2CS and then applying TD-OCC in the two-symbol pattern.

TABLE 24-1 w_(t)(l′) = [w_(t)(0) w_(t)(1)] Antenna Δ φ_(k) Δ φ_(k) OneTwo port p One symbol Two symbol symbol symbol P1 0 0 0 0 [+1] [+1 +1]P2 0 π(└k/2┘) 0 π(└k/2┘) [+1] [+1 +1] P3 1 0 0 0 [+1] [+1 −1] P4 1π(└k/2┘) 0 π(└k/2┘) [+1] [+1 −1] P5 — — 1 0 — [+1 +1] P6 — — 1 π(└k/2┘)— [+1 +1] P7 — — 1 0 — [+1 −1] P8 — — 1 π(└k/2┘) — [+1 −1]

[Table 24-2] shows parameters configured through a method (case 10-2) offirst applying TD-OCC and then applying 2 CS in the two-symbol pattern.In [Table 24-2], Two symbol(*) considers the case in which one-symbolpattern is repeated and a maximum of 4 ports are scheduled in twosymbols, which is a method of considering that it is difficult to applyTD-OCC to the high frequency band.

TABLE 24-2 w_(t)(l′) = [w_(t)(0) w_(t)(1)] Antenna Δ φ_(k) Δ φ_(k) Δφ_(k) One Two Two port p One symbol Two symbol Two symbol(*) symbolsymbol symbol(*) P1 0 0 0 0 0 0 [+1] [+1 +1] [+1 +1] P2 0 π(└k/2┘) 0 0 10 [+1] [+1 −1] [+1 +1] P3 1 0 0 π(└k/2┘) 0 π(└k/2┘) [+1] [+1 +1] [+1 +1]P4 1 π(└k/2┘) 0 π(└k/2┘) 1 π(└k/2┘) [+1] [+1 −1] [+1 +1] P5 — — 1 0 — —— [+1 +1] — P6 — — 1 0 — — — [+1 −1] — P7 — — 1 π(└k/2┘) — — — [+1 +1] —P8 — — 1 π(└k/2┘) — — — [+1 −1] —

The parameters in [Table 15] to [Table 24] correspond to parametervalues in [Equation 25], and it is noted that equations and some valuesmay be differently expressed if the same effect can be obtained throughdifferent expressions.

Next, in the case of a type 2 pattern, the FD-OCC in 2 REs adjacent onthe frequency is the basic structure like the agreement, and in the caseof the two-symbol pattern, TD-OCC({1} and {1−1}) is applied and amaximum of 12 orthogonal DMRS ports are supported. As described above, amethod of supporting a plurality of antenna ports is applied and theDMRS may be mapped to a first OFDM system and a k^(th) subcarrier on thetime as shown in the following equation.a _(k,l) ^((p,μ)) =w _(f)(k′)·w _(t)(l′)·r(m+m ₀)k=k ₀+6m+k′+Δl=l ₀ +l′  [Equation 26]

In [Equation 26], r(m) denotes the DMRS sequence generated in [Equation14] of <Embodiment 2-2>, w_(t)(l′) denotes application of a TD-OCCapplied to the two-symbol pattern, and w_(f)(k′) denotes application of2-FD-OCC in adjacent REs on the frequency. The values varying dependingon the antenna port mapping are presented in detail in the followingtable.

FIG. 29 illustrates an example of a pattern available in type 2according to the antenna port mapping method. Reference numerals 2900,2902, and 2904 indicate antenna ports which can be mapped to differentfrequency locations. Reference numerals 2910 and 2920 indicate examplesof mapping type 2 to one symbol.

Reference numeral 2910 corresponds to a mapping method according to amethod by which DMRS ports P1/P2, P3/P4, and P5/P6 are separated by FDM,and reference numeral 2920 corresponds to a mapping method according toa method by which DMRS ports P1/P4, P2/P5, and P3/P6 are separated byFDM. In reference numerals 2910 and 2920, two ports mapped to adjacenttwo REs on the frequency may be separated using FD-OCC. Specifically,the mapping method 2910 may have the following DMRS density.

-   -   In the case in which 4 REs are used <=two layer transmission    -   In the case in which 8 REs are used > two and <=four layer        transmission    -   In the case in which 12 REs are used > four layer transmission        Unlike the above, the mapping method 2920 may have the following        DMRS density.    -   In the case in which 4 REs are used, one layer transmission    -   In the case in which 8 REs are used, two layer transmission    -   In the case in which 12 REs are used > two layer transmission

Accordingly, the methods 2910 and 2920 may have different DMRS densitiesdepending on the number of transmitted DMRS ports.

Subsequently, reference numerals 2930 to 2970 illustrate examples ofmapping type 2 to two symbols. Reference numeral 2930 corresponds to amapping method according to a method by which DMRS ports P1/P3/P5/P7 andP2/P4/P6/P8 are separated by FDM, and reference numeral 2940 correspondsto a mapping method according to a method by which DRMS portsP1/P3/P5/P6 and P2/P4/P7/P8 are separated by FDM. Reference numeral 2950corresponds to a mapping method according to a method by which DMRSports P1/P2/P5/P7 and P3/P4/P6/P8 are separated by FDM, and referencenumeral 2960 corresponds to a mapping method according to a method bywhich DRMS ports P1/P2/P5/P6 and P3/P4/P7/P8 are separated by FDM. Last,reference numeral 2970 corresponds to a mapping method according to amethod by which DMRS ports P1/P2/P3/P4 and P5/P6/P7/P8 are separated byFDM. In reference numerals 2930 to 2970, the number of ports mapped toadjacent two REs on the frequency, which can be separated, may be amaximum of four through the FD-OCC and the TD-OCC. Specifically, themapping methods 2930 and 2940 may have the following DMRS density.

-   -   In the case in which 8 REs are used <=two layer transmission    -   In the case in which 12 REs are used > two and <=four layer        transmission    -   In the case in which 24 REs are used > four layer transmission        Unlike the above, the mapping methods 2950 and 2960 may have the        following DMRS density.    -   In the case in which 8 REs are used, one layer transmission    -   In the case in which 12 REs are used, two layer transmission    -   In the case in which 24 REs are used > two layer transmission        Unlike the above, the mapping method 2970 may have the following        DMRS density.    -   In the case in which 8 REs are used <=four layer transmission    -   In the case in which 12 REs are used > four and <=eight layer        transmission    -   In the case in which 24 REs are used > eight layer transmission

According to the antenna port mapping method of type 2, it is noted thatthe DMRS density varies depending thereon and the one-symbol pattern andthe two-symbol pattern for the DMRS may use different mapping patternsdepending on the optimized mapping method.

More specifically, a detailed method of configuring parameters in[Equation 26] varying depending on which antenna port mapping method isused by the one-symbol pattern or the two-symbol pattern for the DMRS ispresented. First, available configuration methods of the one-symbolpattern and the two-symbol pattern for the DMRS may be divided into 10methods according to the antenna port mapping method illustrated in FIG.29, and configuration of parameters in [Equation 26] is describedthrough a table.

-   -   Case1: One symbol 2910 and Two symbol 2930    -   Case2: One symbol 2910 and Two symbol 2940    -   Case3: One symbol 2910 and Two symbol 2950    -   Case4: One symbol 2910 and Two symbol 2960    -   Case5: One symbol 2910 and Two symbol 2970    -   Case6: One symbol 2920 and Two symbol 2930    -   Case7: One symbol 2920 and Two symbol 2940    -   Case8: One symbol 2920 and Two symbol 2950    -   Case9: One symbol 2920 and Two symbol 2960    -   Case10: One symbol 2920 and Two symbol 2970

Further, the two-symbol pattern may consider additional cases accordingto priories of FD-OCC and TD-OCC applied to antenna ports withinadjacent two REs on the frequency.

-   -   Method 1: first apply FD-OCC and then apply TD-OCC in two-symbol        pattern    -   Method 2: first apply TD-OCC and then apply FD-OCC in two-symbol        pattern

[Table 25-1] and [Table 25-2] below show configuration values ofparameters in [Equation 26] according to case 1. [Table 25-1] showsparameters configured through a method (case 1-1) of first applyingFD-OCC and then applying TD-OCC in the two-symbol pattern.

TABLE 25-1 Antenna port w_(t)(l′) = [w_(t)(0) w_(t)(1)] p Δ w_(f)(l′) =[w_(f)(0) w_(f)(1)] One symbol Two symbol P1 0 [+1 +1] [+1] [+1 +1] P2 0[+1 −1] [+1] [+1 +1] P3 2 [+1 +1] [+1] [+1 +1] P4 2 [+1 −1] [+1] [+1 +1]P5 4 [+1 +1] [+1] [+1 +1] P6 4 [+1 −1] [+1] [+1 +1] P7 0 [+1 +1] — [+1−1] P8 0 [+1 −1] — [+1 −1] P9 2 [+1 +1] — [+1 −1] P10 2 [+1 −1] — [+1−1] P11 4 [+1 +1] — [+1 −1] P12 4 [+1 −1] — [+1 −1]

[Table 25-2] shows parameters configured through a method (case 1-2) offirst applying TD-OCC and then applying FD-OCC in the two-symbolpattern. In [Table 25-2], Two symbol(*) considers the case in whichone-symbol pattern is repeated and a maximum of 6 ports are scheduled intwo symbols, which is a method of considering that it is difficult toapply TD-OCC to the high frequency band.

TABLE 25-2 Δ w_(f)(l′) = [w_(f)(0) w_(f)(1)] w_(t)(l′) = [w_(t)(0)w_(t)(1)] Antenna One Two Two One Two Two One Two Two port p symbolsymbol symbol(*) symbol symbol symbol(*) symbol symbol symbol(*) P1 0 00 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 0 0 0 [+1 −1] [+1 +1][+1 −1] [+1] [+1 −1] [+1 +1] P3 2 2 2 [+1 +1] [+1 +1] [+1 +1] [+1] [+1+1] [+1 +1] P4 2 2 2 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P5 4 44 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P6 4 4 4 [+1 −1] [+1 +1][+1 −1] [+1] [+1 −1] [+1 +1] P7 — 0 — — [+1 −1] — — [+1 +1] — P8 — 0 — —[+1 −1] — — [+1 −1] — P9 — 2 — — [+1 −1] — — [+1 +1] — P10 — 2 — — [+1−1] — — [+1 −1] — P11 — 4 — — [+1 −1] — — [+1 +1] — P12 — 4 — — [+1 −1]— — [+1 −1] —

[Table 26-1] and [Table 26-2] below show configuration values ofparameters in [Equation 26] according to case 2. [Table 26-1] showsparameters configured through a method (case 2-1) of first applyingFD-OCC and then applying TD-OCC in the two-symbol pattern.

TABLE 26-1 Antenna port w_(t)(l′) = [w_(t)(0) w_(t)(1)] p Δ w_(f)(l′) =[w_(f)(0) w_(f)(1)] One symbol Two symbol P1 0 [+1 +1] [+1] [+1 +1] P2 0[+1 −1] [+1] [+1 +1] P3 2 [+1 +1] [+1] [+1 +1] P4 2 [+1 −1] [+1] [+1 +1]P5 4 [+1 +1] [+1] [+1 +1] P6 4 [+1 −1] [+1] [+1 +1] P7 0 [+1 +1] — [+1−1] P8 2 [+1 +1] — [+1 −1] P9 4 [+1 +1] — [+1 −1] P10 0 [+1 −1] — [+1−1] P11 2 [+1 −1] — [+1 −1] P12 4 [+1 −1] — [+1 −1]

[Table 26-2] shows parameters configured through a method (case 2-2) offirst applying TD-OCC and then applying FD-OCC in the two-symbolpattern. In [Table 26-2], Two symbol(*) considers the case in whichone-symbol pattern is repeated and a maximum of 6 ports are scheduled intwo symbols, which is a method of considering that it is difficult toapply TD-OCC to the high frequency band.

TABLE 26-2 Δ w_(f)(l′) = [w_(f)(0) w_(f)(1)] w_(t)(l′) = [w_(t)(0)w_(t)(1)] Antenna One Two Two One Two Two One Two Two port p symbolsymbol symbol(*) symbol symbol symbol(*) symbol symbol symbol(*) P1 0 00 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 0 0 0 [+1 −1] [+1 +1][+1 −1] [+1] [+1 −1] [+1 +1] P3 2 2 2 [+1 +1] [+1 +1] [+1 +1] [+1] [+1+1] [+1 +1] P4 2 2 2 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P5 4 44 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P6 4 4 4 [+1 −1] [+1 +1][+1 −1] [+1] [+1 −1] [+1 +1] P7 0 — [+1 −1] — — [+1 +1] — P8 2 — [+1 −1]— — [+1 −1] — P9 4 — [+1 −1] — — [+1 +1] — P10 0 — [+1 −1] — — [+1 −1] —P11 2 — [+1 −1] — — [+1 +1] — P12 4 — [+1 −1] — — [+1 −1] —

[Table 27-1] and [Table 27-2] below show configuration values ofparameters in [Equation 26] according to case 3. [Table 27-1] showsparameters configured through a method of first applying FD-OCC and thenapplying TD-OCC in the two-symbol pattern.

TABLE 27-1 Δ w_(t)(l′) = [w_(t)(0) w_(t)(1)] One Two Two w_(f) (l′) =[w_(f)(0) w_(f)(1)] One Two Antenna sym- sym- sym- One Two Two sym- Twosym- port_(p) bol bol bol (*) symbol symbol symbol (*) bol symbol bol(*) P1 0 0 0 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 0 2 0 [+1−1] [+1 +1] [+1 −1] [+1] [+1 +1] [+1 +1] P3 2 4 2 [+1 +1] [+1 +1] [+1+1] [+1] [+1 +1] [+1 +1] P4 2 0 2 [+1 −1] [+1 −1] [+1 −1] [+1] [+1 +1][+1 +1] P5 4 2 4 [+1 +1] [+1 −1] [+1 +1] [+1] [+1 +1] [+1 +1] P6 4 4 4[+1 −1] [+1 −1] [+1 −1] [+1] [+1 +1] [+1 +1] P7 — 0 — [+1 +1] — — [+1−1] — P8 — 2 — [+1 +1] — — [+1 −1] — P9 — 4 — [+1 +1] — — [+1 −1] — P10— 0 — [+1 −1] — — [+1 −1] — P11 — 2 — [+1 −1] — — [+1 −1] — P12 — 4 —[+1 −1] — — [+1 −1] —

[Table 27-2] shows parameters configured through a method (case 3-2) offirst applying TD-OCC and then applying FD-OCC in the two-symbolpattern. In [Table 27-2], Two symbol(*) considers the case in whichone-symbol pattern is repeated and a maximum of 6 ports are scheduled intwo symbols, which is a method of considering that it is difficult toapply TD-OCC to the high frequency band.

TABLE 27-2 Δ w_(t)(l′) = [w_(t)(0) w_(t)(1)] One Two Two w_(f) (l′) =[w_(f)(0) w_(f)(1)] One Two Antenna sym- sym- sym- One Two Two sym- Twosym- port_(p) bol bol bol (*) symbol symbol symbol (*) bol symbol bol(*) P1 0 0 0 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 0 2 0 [+1−1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P3 2 4 2 [+1 +1] [+1 +1] [+1+1] [+1] [+1 +1] [+1 +1] P4 2 0 2 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1][+1 +1] P5 4 2 4 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P6 4 4 4[+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P7 — 0 — [+1 −1] — — [+1+1] — P8 — 2 — [+1 −1] — — [+1 −1] — P9 — 4 — [+1 −1] — — [+1 +1] — P10— 0 — [+1 −1] — — [+1 −1] — P11 — 2 — [+1 −1] — — [+1 +1] — P12 — 4 —[+1 −1] — — [+1 −1] —

[Table 28-1] and [Table 28-2] below show configuration values ofparameters in [Equation 26] according to case 4. [Table 28-1] showsparameters configured through a method (case 4-1) of first applyingFD-OCC and then applying TD-OCC in the two-symbol pattern.

TABLE 28-1 Δ w_(t)(l′) = [w_(t)(0) w_(t)(1)] One Two Two w_(f) (l′) =[w_(f)(0) w_(f)(1)] One Two Antenna sym- sym- sym- One Two Two sym- Twosym- port_(p) bol bol bol (*) symbol symbol symbol (*) bol symbol bol(*) P1 0 0 0 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 0 2 0 [+1−1] [+1 +1] [+1 −1] [+1] [+1 +1] [+1 +1] P3 2 4 2 [+1 +1] [+1 +1] [+1+1] [+1] [+1 +1] [+1 +1] P4 2 0 2 [+1 −1] [+1 −1] [+1 −1] [+1] [+1 +1][+1 +1] P5 4 2 4 [+1 +1] [+1 −1] [+1 +1] [+1] [+1 +1] [+1 +1] P6 4 4 4[+1 −1] [+1 −1] [+1 −1] [+1] [+1 +1] [+1 +1] P7 — 0 — [+1 +1] — — [+1−1] — P8 — 0 — [+1 −1] — — [+1 −1] — P9 — 2 — [+1 +1] — — [+1 −1] — P10— 2 — [+1 −1] — — [+1 −1] — P11 — 4 — [+1 +1] — — [+1 −1] — P12 — 4 —[+1 −1] — — [+1 −1] —

[Table 28-2] shows parameters configured through a method (case 4-2) offirst applying TD-OCC and then applying FD-OCC in the two-symbolpattern. In [Table 28-2], Two symbol(*) considers the case in whichone-symbol pattern is repeated and a maximum of 6 ports are scheduled intwo symbols, which is a method of considering that it is difficult toapply TD-OCC to the high frequency band.

TABLE 28-2 Δ w_(t)(l′) = [w_(t)(0) w_(t)(1)] One Two Two w_(f) (l′) =[w_(f)(0) w_(f)(1)] One Two Antenna sym- sym- sym- One Two Two sym- Twosym- port_(p) bol bol bol (*) symbol symbol symbol (*) bol symbol bol(*) P1 0 0 0 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 0 2 0 [+1−1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P3 2 4 2 [+1 +1] [+1 +1] [+1+1] [+1] [+1 +1] [+1 +1] P4 2 0 2 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1][+1 +1] P5 4 2 4 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P6 4 4 4[+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P7 — 0 — [+1 −1] — — [+1+1] — P8 — 0 — [+1 −1] — — [+1 −1] — P9 — 2 — [+1 −1] — — [+1 +1] — P10— 2 — [+1 −1] — — [+1 −1] — P11 — 4 — [+1 −1] — — [+1 +1] — P12 — 4 —[+1 −1] — — [+1 −1] — (*) Scheduled up to 6 ports in two symbols

[Table 29-1] and [Table 29-2] below show configuration values ofparameters in [Equation 26] according to case 5. [Table 29-1] showsparameters configured through a method (case 5-1) of first applyingFD-OCC and then applying TD-OCC in the two-symbol pattern.

TABLE 29-1 Δ w_(t)(l′) = [w_(t)(0) w_(t)(1)] One Two Two w_(f) (l′) =[w_(f)(0) w_(f)(1)] One Two Antenna sym- sym- sym- One Two Two sym- Twosym- port_(p) bol bol bol (*) symbol symbol symbol (*) bol symbol bol(*) P1 0 0 0 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 0 2 0 [+1−1] [+1 −1] [+1 −1] [+1] [+1 +1] [+1 +1] P3 2 4 2 [+1 +1] [+1 +1] [+1+1] [+1] [+1 +1] [+1 +1] P4 2 0 2 [+1 −1] [+1 −1] [+1 −1] [+1] [+1 +1][+1 +1] P5 4 2 4 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P6 4 4 4[+1 −1] [+1 −1] [+1 −1] [+1] [+1 +1] [+1 +1] P7 — 0 — [+1 +1] — — [+1−1] — P8 — 2 — [+1 −1] — — [+1 −1] — P9 — 4 — [+1 +1] — — [+1 −1] — P10— 0 — [+1 −1] — — [+1 −1] — P11 — 2 — [+1 +1] — — [+1 −1] — P12 — 4 —[+1 −1] — — [+1 −1] —

[Table 29-2] shows parameters configured through a method (case 5-2) offirst applying TD-OCC and then applying FD-OCC in the two-symbolpattern. In [Table 29-2], Two symbol(*) considers the case in whichone-symbol pattern is repeated and a maximum of 6 ports are scheduled intwo symbols, which is a method of considering that it is difficult toapply TD-OCC to the high frequency band.

TABLE 29-2 Δ w_(t)(l′) = [w_(t)(0) w_(t)(1)] One Two Two w_(f) (l′) =[w_(f)(0) w_(f)(1)] One Two Antenna sym- sym- sym- One Two Two sym- Twosym- port_(p) bol bol bol (*) symbol symbol symbol (*) bol symbol bol(*) P1 0 0 0 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 0 0 0 [+1−1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P3 2 0 2 [+1 +1] [+1 +1] [+1+1] [+1] [+1 +1] [+1 +1] P4 2 0 2 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1][+1 +1] P5 4 2 4 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P6 4 2 4[+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P7 — 2 — [+1 −1] — — [+1+1] — P8 — 2 — [+1 −1] — — [+1 −1] — P9 — 4 — [+1 −1] — — [+1 +1] — P10— 4 — [+1 −1] — — [+1 −1] — P11 — 4 — [+1 −1] — — [+1 +1] — P12 — 4 —[+1 −1] — — [+1 −1] —

[Table 30-1] and [Table 30-2] below show configuration values ofparameters in [Equation 26] according to case 6. [Table 30-1] showsparameters configured through a method (case 6-1) of first applyingFD-OCC and then applying TD-OCC in the two-symbol pattern.

TABLE 30-1 Δ w_(t)(l′) = [w_(t)(0) w_(t)(1)] One Two Two w_(f) (l′) =[w_(f)(0) w_(f)(1)] One Two Antenna sym- sym- sym- One Two Two sym- Twosym- port_(p) bol bol bol (*) symbol symbol symbol (*) bol symbol bol(*) P1 0 0 0 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 2 0 2 [+1+1] [+1 −1] [+1 +1] [+1] [+1 +1] [+1 +1] P3 4 2 4 [+1 +1] [+1 +1] [+1+1] [+1] [+1 +1] [+1 +1] P4 0 2 0 [+1 −1] [+1 −1] [+1 −1] [+1] [+1 +1][+1 +1] P5 2 4 2 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 +1] [+1 +1] P6 4 4 4[+1 −1] [+1 −1] [+1 −1] [+1] [+1 +1] [+1 +1] P7 — 0 — [+1 +1] — — [+1−1] — P8 — 0 — [+1 −1] — — [+1 −1] — P9 — 2 — [+1 +1] — — [+1 −1] — P10— 2 — [+1 −1] — — [+1 −1] — P11 — 4 — [+1 +1] — — [+1 −1] — P12 — 4 —[+1 −1] — — [+1 −1] —

[Table 30-2] shows parameters configured through a method (case 6-2) offirst applying TD-OCC and then applying FD-OCC in the two-symbolpattern. In [Table 30-2], Two symbol(*) considers the case in whichone-symbol pattern is repeated and a maximum of 6 ports are scheduled intwo symbols, which is a method of considering that it is difficult toapply TD-OCC to the high frequency band.

TABLE 30-2 Δ w_(t)(l′) = [w_(t)(0) w_(t)(1)] One Two Two w_(f) (l′) =[w_(f)(0) w_(f)(1)] One Two Antenna sym- sym- sym- One Two Two sym- Twosym- port_(p) bol bol bol (*) symbol symbol symbol (*) bol symbol bol(*) P1 0 0 0 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 2 0 2 [+1+1] [+1 +1] [+1 +1] [+1] [+1 −1] [+1 +1] P3 4 2 4 [+1 +1] [+1 +1] [+1+1] [+1] [+1 +1] [+1 +1] P4 0 2 0 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1][+1 +1] P5 2 4 2 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 +1] [+1 +1] P6 4 4 4[+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P7 — 0 — — [+1 −1] — — [+1+1] — P8 — 0 — — [+1 −1] — — [+1 −1] — P9 — 2 — — [+1 −1] — — [+1 +1] —P10 — 2 — — [+1 −1] — — [+1 −1] — P11 — 4 — — [+1 −1] — — [+1 +1] — P12— 4 — — [+1 −1] — — [+1 −1] —

[Table 31-1] and [Table 31-2] below show configuration values ofparameters in [Equation 26] according to case 7. [Table 31-1] showsparameters configured through a method (case 7-1) of first applyingFD-OCC and then applying TD-OCC in the two-symbol pattern.

TABLE 31-1 Δ w_(t)(l′) = [w_(t)(0) w_(t)(1)] One Two Two w_(f) (l′) =[w_(f)(0) w_(f)(1)] One Two Antenna sym- sym- sym- One Two Two sym- Twosym- port_(p) bol bol bol (*) symbol symbol symbol (*) bol symbol bol(*) P1 0 0 0 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 2 0 2 [+1+1] [+1 −1] [+1 +1] [+1] [+1 +1] [+1 +1] P3 4 2 4 [+1 +1] [+1 +1] [+1+1] [+1] [+1 +1] [+1 +1] P4 0 2 0 [+1 −1] [+1 −1] [+1 −1] [+1] [+1 +1][+1 +1] P5 2 4 2 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 +1] [+1 +1] P6 4 4 4[+1 −1] [+1 −1] [+1 −1] [+1] [+1 +1] [+1 +1] P7 0 0 — [+1 +1] — — [+1−1] — P8 2 2 — [+1 +1] — — [+1 −1] — P9 4 4 — [+1 +1] — — [+1 −1] — P100 0 — [+1 −1] — — [+1 −1] — P11 2 2 — [+1 −1] — — [+1 −1] — P12 4 4 —[+1 −1] — — [+1 −1] —

[Table 31-2] shows parameters configured through a method (case 7-2) offirst applying TD-OCC and then applying FD-OCC in the two-symbolpattern. In [Table 31-2], Two symbol(*) considers the case in whichone-symbol pattern is repeated and a maximum of 6 ports are scheduled intwo symbols, which is a method of considering that it is difficult toapply TD-OCC to the high frequency band.

TABLE 31-2 Δ w_(t)(l′) = [w_(t)(0) w_(t)(1)] One Two Two w_(f) (l′) =[w_(f)(0) w_(f)(1)] One Two Antenna sym- sym- sym- One Two Two sym- Twosym- port_(p) bol bol bol (*) symbol symbol symbol (*) bol symbol bol(*) P1 0 0 0 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 2 0 2 [+1+1] [+1 +1] [+1 +1] [+1] [+1 −1] [+1 +1] P3 4 2 4 [+1 +1] [+1 +1] [+1+1] [+1] [+1 +1] [+1 +1] P4 0 2 0 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1][+1 +1] P5 2 4 2 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 +1] [+1 +1] P6 4 4 4[+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P7 — 0 — — [+1 −1] — — [+1+1] — P8 — 2 — — [+1 −1] — — [+1 −1] — P9 — 4 — — [+1 −1] — — [+1 +1] —P10 — 0 — — [+1 −1] — — [+1 −1] — P11 — 2 — — [+1 −1] — — [+1 +1] — P12— 4 — — [+1 −1] — — [+1 −1] —

[Table 32-1] and [Table 32-2] below show configuration values ofparameters in [Equation 26] according to case 8. [Table 32-1] showsparameters configured through a method (case 8-1) of first applyingFD-OCC and then applying TD-OCC in the two-symbol pattern.

TABLE 32-1 Antenna port w_(t)(l′) = [w_(t)(0) w_(t)(1)] p Δ w_(f)(l′) =[w_(f)(0) w_(f)(1)] One symbol Two symbol P1 0 [+1 +1] [+1] [+1 +1] P2 2[+1 +1] [+1] [+1 +1] P3 4 [+1 +1] [+1] [+1 +1] P4 0 [+1 −1] [+1] [+1 +1]P5 2 [+1 −1] [+1] [+1 +1] P6 4 [+1 −1] [+1] [+1 +1] P7 0 [+1 +1] — [+1−1] P8 2 [+1 +1] — [+1 −1] P9 4 [+1 +1] — [+1 −1] P10 0 [+1 −1] — [+1−1] P11 2 [+1 −1] — [+1 −1] P12 4 [+1 −1] — [+1 −1]

[Table 32-2] shows parameters configured through a method (case 8-2) offirst applying TD-OCC and then applying FD-OCC in the two-symbolpattern. In [Table 32-2], Two symbol(*) considers the case in whichone-symbol pattern is repeated and a maximum of 6 ports are scheduled intwo symbols, which is a method of considering that it is difficult toapply TD-OCC to the high frequency band.

TABLE 32-2 Δ w_(t)(l′) = [w_(t)(0) w_(t)(1)] One Two Two w_(f) (l′) =[w_(f)(0) w_(f)(1)] One Two Antenna sym- sym- sym- One Two Two sym- Twosym- port_(p) bol bol bol (*) symbol symbol symbol (*) bol symbol bol(*) P1 0 0 0 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 2 2 2 [+1+1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P3 4 4 4 [+1 +1] [+1 +1] [+1+1] [+1] [+1 +1] [+1 +1] P4 0 0 0 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1][+1 +1] P5 2 2 2 [+1 −1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P6 4 4 4[+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P7 — 0 — [+1 −1] — — [+1+1] — P8 — 2 — [+1 −1] — — [+1 −1] — P9 — 4 — [+1 −1] — — [+1 +1] — P10— 0 — [+1 −1] — — [+1 −1] — P11 — 2 — [+1 −1] — — [+1 +1] — P12 — 4 —[+1 −1] — — [+1 −1] —

[Table 33-1] and [Table 33-2] below show configuration values ofparameters in [Equation 26] according to case 9. [Table 33-1] showsparameters configured through a method (case 9-1) of first applyingFD-OCC and then applying TD-OCC in the two-symbol pattern.

TABLE 33-1 Antenna port w_(t)(l′) = [w_(t)(0) w_(t)(1)] p Δ w_(f)(l′) =[w_(f)(0) w_(f)(1)] One symbol Two symbol P1 0 [+1 +1] [+1] [+1 +1] P2 2[+1 +1] [+1] [+1 +1] P3 4 [+1 +1] [+1] [+1 +1] P4 0 [+1 −1] [+1] [+1 +1]P5 2 [+1 −1] [+1] [+1 +1] P6 4 [+1 −1] [+1] [+1 +1] P7 0 [+1 +1] — [+1−1] P8 0 [+1 −1] — [+1 −1] P9 2 [+1 +1] — [+1 −1] P10 2 [+1 −1] — [+1−1] P11 4 [+1 +1] — [+1 −1] P12 4 [+1 −1] — [+1 −1]

[Table 33-2] shows parameters configured through a method (case 9-2) offirst applying TD-OCC and then applying FD-OCC in the two-symbolpattern. In [Table 33-2], Two symbol(*) considers the case in whichone-symbol pattern is repeated and a maximum of 6 ports are scheduled intwo symbols, which is a method of considering that it is difficult toapply TD-OCC to the high frequency band.

TABLE 33-2 Δ w_(f)(l′) = [w_(f)(0) w_(f)(1)] w_(t)(l′) = [w_(t)(0)w_(t)(1)] Two Two Two Antenna port One Two symbol One Two symbol One Twosymbol p symbol symbol (*) symbol symbol (*) symbol symbol (*) P1 0 0 0[+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 2 2 2 [+1 +1] [+1 +1][+1 +1] [+1] [+1 −1] [+1 +1] P3 4 4 4 [+1 +1] [+1 +1] [+1 +1] [+1] [+1+1] [+1 +1] P4 0 0 0 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P5 2 22 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 +1] [+1 +1] P6 4 4 4 [+1 −1] [+1 +1][+1 −1] [+1] [+1 −1] [+1 +1] P7 — 0 — [+1 −1] — — [+1 +1] — P8 — 0 — [+1−1] — — [+1 −1] — P9 — 2 — [+1 −1] — — [+1 +1] — P10 — 2 — [+1 −1] — —[+1 −1] — P11 — 4 — [+1 −1] — — [+1 +1] — P12 — 4 — [+1 −1] — — [+1 −1]—

[Table 34-1] and [Table 34-2] below show configuration values ofparameters in [Equation 26] according to case 10. [Table 34-1] showsparameters configured through a method (case 10-1) of first applyingFD-OCC and then applying TD-OCC in the two-symbol pattern.

TABLE 34-1 Δ w_(t)(l′) = [w_(t)(0) w_(t)(1)] One Two Two w_(f) (l′) =[w_(f)(0) w_(f)(1)] One Two Antenna sym- sym- sym- One Two Two sym- Twosym- port_(p) bol bol bol (*) symbol symbol symbol (*) bol symbol bol(*) P1 0 0 0 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 2 0 2 [+1+1] [+1 −1] [+1 +1] [+1] [+1 +1] [+1 +1] P3 4 0 4 [+1 +1] [+1 +1] [+1+1] [+1] [+1 +1] [+1 +1] P4 0 0 0 [+1 −1] [+1 −1] [+1 −1] [+1] [+1 +1][+1 +1] P5 2 2 2 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 +1] [+1 +1] P6 4 2 4[+1 −1] [+1 −1] [+1 −1] [+1] [+1 +1] [+1 +1] P7 — 2 — [+1 +1] — — [+1−1] — P8 — 2 — [+1 −1] — — [+1 −1] — P9 — 4 — [+1 +1] — — [+1 −1] — P10— 4 — [+1 −1] — — [+1 −1] — P11 — 4 — [+1 +1] — — [+1 −1] — P12 — 4 —[+1 −1] — — [+1 −1] —

[Table 34-2] shows parameters configured through a method (case 10-2) offirst applying TD-OCC and then applying FD-OCC in the two-symbolpattern. In [Table 34-2], Two symbol(*) considers the case in whichone-symbol pattern is repeated and a maximum of 6 ports are scheduled intwo symbols, which is a method of considering that it is difficult toapply TD-OCC to the high frequency band.

TABLE 34-2 Δ w_(t)(l′) = [w_(t)(0) w_(t)(1)] One Two Two w_(f) (l′) =[w_(f)(0) w_(f)(1)] One Two Antenna sym- sym- sym- One Two Two sym- Twosym- port_(p) bol bol bol (*) symbol symbol symbol (*) bol symbol bol(*) P1 0 0 0 [+1 +1] [+1 +1] [+1 +1] [+1] [+1 +1] [+1 +1] P2 2 0 2 [+1+1] [+1 +1] [+1 +1] [+1] [+1 −1] [+1 +1] P3 4 0 4 [+1 +1] [+1 +1] [+1+1] [+1] [+1 +1] [+1 +1] P4 0 0 0 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1][+1 +1] P5 2 2 2 [+1 −1] [+1 +1] [+1 −1] [+1] [+1 +1] [+1 +1] P6 4 2 4[+1 −1] [+1 +1] [+1 −1] [+1] [+1 −1] [+1 +1] P7 — 2 — [+1 −1] — — [+1+1] — P8 — 2 — [+1 −1] — — [+1 −1] — P9 — 4 — [+1 −1] — — [+1 +1] — P10— 4 — [+1 −1] — — [+1 −1] — P11 — 4 — [+1 −1] — — [+1 +1] — P12 — 4 —[+1 −1] — — [+1 −1] —

The parameters in [Table 25] to [Table 34] above correspond to parametervalues in [Equation 26], and it is noted that equations and some valuesmay be differently expressed if the same effect can be obtained throughdifferent expressions.

Embodiment 2-6

<Embodiment 2-6> suggests a DMRS power boosting method based on the DMRSpattern described in <Embodiment 2-5>. It is noted that the DMRS powerboosting method may vary depending on the DMRS pattern. As illustratedin FIG. 28, in the case of the type 1 DMRS pattern, comb 2 and 2 CS maybe used, and if the number of data transmission layers is larger than 2,transmission can be performed with DMRS power increased two timescompared to data.

FIG. 30 illustrates an example of DMRS transmission for the type 1 DMRSpattern.

Specifically, as indicated by reference numeral 3010, if the number ofdata transmission layers is 4, the DRMS is transmitted through only 2ports in REs in which the DMRS is transmitted in the case of referencenumeral 2810, so that transmission can be performed with increased powertwo times. This is applied to all patterns illustrated in FIG. 28. Asdescribed above, in the case of the type 1 DMRS pattern, DMRS powerboosting can be presented at a ratio of a PDSCH (data) and energy perresource element (EPRE) of a UE-specific RS (DMRS) as described below.

-   -   For DMRS configuration type1, if UE-specific RSs are present in        the PRBs upon which the corresponding PDSCH is mapped, the UE        may assume the ratio of PDSCH EPRE to UE-specific RS EPRE within        each OFDM symbol containing the UE-specific RS.    -   0 dB for number of transmission layers less than or equal to two    -   and −3 dB otherwise

Unlike the above, as illustrated in FIG. 29, in the case of the type 2DMRS pattern, OCC is applied to two adjacent REs on the frequency, andif the number of transmission layers is larger than 2, transmission canbe performed with DMRS power increased two times compared to data. Ifthe number of data transmission layers is larger than 4, transmissioncan be performed with DMRS power increased three times compared to data.Specifically, as indicated by reference numeral 3020, if the number ofdata transmission layers is 6, the DRMS is transmitted through only 2ports in REs in which the DMRS is transmitted in the case of referencenumeral 2910, so that transmission can be performed with DMRS powerincreased three times. This is applied to all patterns illustrated inFIG. 29. As described above, in the case of the type 2 DMRS pattern,DMRS power boosting can be presented at a ratio of a PDSCH (data) andEPRE of a UE-specific RS (DMRS) as described below.

-   -   For DMRS configuration type1, if UE-specific RSs are present in        the PRBs upon which the corresponding PDSCH is mapped, the UE        may assume the ratio of PDSCH EPRE to UE-specific RS EPRE within        each OFDM symbol containing the UE-specific RS.    -   0.0 dB for number of transmission layers less than or equal to        two    -   −3 dB for number of transmission layers less than or equal to        two    -   and −4.77 dB otherwise

Embodiment 2-7

<Embodiment 2-7> proposes a DMRS information signaling method based onthe DMRS pattern described in <Embodiment 2-5>. The DMRS signalingmethod may vary depending on the DMRS pattern. DMRS signalinginformation may include the following.

-   -   Number of layers & port number    -   SCID (Scrambling ID)    -   One symbol and two symbol indicators

The number of layers and the port number are information required forSU/MU dynamic switching and MU operation. As described in <Embodiment2-5>, the type 1 DMRS pattern is a method of supporting a maximum offour ports in one symbol and a maximum of eight ports in two symbols,and the type 2 DMRS pattern is a method of supporting a maximum of sixport in one symbol and a maximum of twelve ports in two symbols.Accordingly, the type 1 and type 2 DMRS patterns have different totalnumbers of orthogonal DMRS layers and different port numbers. Further,the SCID is a parameter which can be used for Coordinated Multi-Point(CoMP) operation, and may function as a virtual cell ID and identify theDMRS from adjacent cells. Although one-bit SCID is used in the LTEsystem, the number of SCID bits may increase in the NR system. Last, onesymbol and two symbol indicators have the DMRS pattern consisting of onesymbol or two symbols. Since two symbols can be configured even in lowlayer transmission, the base station should signal information thereonto the UE through one bit.

Among the information, the number of layers, the port number, and theSCID are information requiring dynamic switching and thus should bedynamically signaled through DCI. However, one symbol and two symbolindicators may be configured through a higher layer or dynamicallysignaled through DCI. If one symbol and two symbol indicators areconfigured through the higher layer, operation of the DMRS through onesymbol or two symbols may be limited.

Hereinafter, difference between type 1 and type 2 will be described onthe basis of a signaling method according to the number of layers andthe port number among the DMRS information. More specifically, in thefollowing embodiment, the number of bits described below is used tosignal information on the number of layers and the port number withrespect to type 1 and type 2.

-   -   Type 1: number of layers and port number→4 bits    -   Type 2: number of layers and port number→5 bits

At this time, an amount of information of 1 bit is different dependingon the configuration of type 1 and type 2, so that a total number ofbits of DCI may vary depending on whether the DMRS pattern is configuredas type 1 or type 2 through the higher layer. Alternatively, throughzero padding, the number of required DCI bits may be configured to fit alarger side in the case of type 1 or type 2.

As described above, the type 1 DMRS pattern is a method supporting amaximum of four ports in one symbol and a maximum of eight ports in twosymbols, and [Table 35] shows a DMRS table design method when a maximumnumber of MU-MIMO layers supported per UE is 2 in the case in whichMU-MIMO is supported using eight orthogonal ports for the type 1 DMRSpattern.

TABLE 35 One Codeword: Two Codewords: Codeword 0 enabled, Codeword 0enabled, Codeword 1 disabled Codeword 1 enabled Value Message ValueMessage 0 1 layer, P1 0 5 layer, P1-P5 1 1 layer, P2 1 6 layer, P1-P6 21 layer, P3 2 7 layer, P1-P7 3 1 layer, P4 3 8 layer, P1-P8 4 1 layer,P5 4 Reserved 5 1 layer, P6 5 Reserved 6 1 layer, P7 6 Reserved 7 1layer, P8 7 Reserved 8 2 layer, P1-P2 8 Reserved 9 2 layer, P3-P4 9Reserved 10 2 layer, P5-P6 10 Reserved 11 2 layer, P7-P8 11 Reserved 123 layer, P1-P3 12 Reserved 13 4 layer, P1-P4 13 Reserved 14 Reserved 14Reserved 15 Reserved 15 Reserved

Unlike the above, [Table 36] shows a DMRS table design method when amaximum number of MU-MIMO layers supported per UE is 4 in the case inwhich MU-MIMO is supported using 8 orthogonal ports for the type 1 DMRSpattern.

TABLE 36 One Codeword: Two Codewords: Codeword 0 enabled, Codeword 0enabled, Codeword 1 disabled Codeword 1 enabled Value Message ValueMessage 0 1 layer, P1 0 5 layer, P1-P5 1 1 layer, P2 1 6 layer, P1-P6 21 layer, P3 2 7 layer, P1-P7 3 1 layer, P4 3 8 layer, P1-P8 4 1 layer,P5 4 Reserved 5 1 layer, P6 5 Reserved 6 1 layer, P7 6 Reserved 7 1layer, P8 7 Reserved 8 2 layer, P1-P2 8 Reserved 9 2 layer, P3-P4 9Reserved 10 2 layer, P5-P6 10 Reserved 11 2 layer, P7-P8 11 Reserved 123 layer, P1-P3 12 Reserved 13 3 layer, P4-P6 13 Reserved 14 4 layer,P1-P4 14 Reserved 15 4 layer, P5-P8 15 Reserved

As described above, the type 2 DMRS pattern is a method supporting amaximum of six ports in one symbol and a maximum of twelve ports in twosymbols, and [Table 37] shows a DMRS table design method when a maximumnumber of MU-MIMO layers supported per UE is 2 in the case in whichMU-MIMO is supported using twelve orthogonal ports for the type 2 DMRSpattern. In this case, the number of cases in which the number ofMU-MIMO layers supported per UE is 1 is expressed as 12 and the numberof cases in which the number of MU-MIMO layers supported per UE is 2 isexpressed as 6.

TABLE 37 One Codeword: Two Codewords: Codeword 0 enabled, Codeword 0enabled, Codeword 1 disabled Codeword 1 enabled Value Message ValueMessage 0 1 layer, P1 0 5 layers, P1-5 1 1 layer, P2 1 6 layers, P1-6 21 layer, P3 2 7 layers, P1-7 3 1 layer, P4 3 8 layers, P1-8 4 1 layer,P5 4 Reserved 5 1 layer, P6 5 Reserved 6 1 layer, P7 6 Reserved 7 1layer, P8 7 Reserved 8 1 layer, P9 8 Reserved 9 1 layer, P10 9 Reserved10 1 layer, P11 10 Reserved 11 1 layer, P12 11 Reserved 12 2 layers,P1-2 12 Reserved 13 2 layers, P3-4 13 Reserved 14 2 layers, P5-6 14Reserved 15 2 layers, P7-8 15 Reserved 16 2 layers, P9-10 16 Reserved 172 layers, P11-12 17 Reserved 18 3 layers, P1-3 18 Reserved 19 4 layers,P1-4 19 Reserved 20 Reserved 20 Reserved 21 Reserved 21 Reserved 22Reserved 22 Reserved 23 Reserved 23 Reserved 24 Reserved 24 Reserved 25Reserved 25 Reserved 26 Reserved 26 Reserved 27 Reserved 27 Reserved 28Reserved 28 Reserved 29 Reserved 29 Reserved 30 Reserved 30 Reserved 31Reserved 31 Reserved

Unlike the above, [Table 38] shows a DMRS table design method when amaximum number of MU-MIMO layers supported per UE is 4 in the case inwhich MU-MIMO is supported using twelve orthogonal ports for the type 2DMRS pattern. In this case, the number of cases in which the number ofMU0MIMO layers supported per UE 1 is expressed as 12, the number ofcases in which the number of MU0MIMO layers supported per UE 2 isexpressed as 6, the number of cases in which the number of MU0MIMOlayers supported per UE 3 is expressed as 4, and the number of cases inwhich the number of MU0MIMO layers supported per UE 4 is expressed as 3.

TABLE 38 One Codeword: Two Codewords: Codeword 0 enabled, Codeword 0enabled, Codeword 1 disabled Codeword 1 enabled Value Message ValueMessage 0 1 layer, P1 0 5 layers, P1-5 1 1 layer, P2 1 6 layers, P1-6 21 layer, P3 2 7 layers, P1-7 3 1 layer, P4 3 8 layers, P1-8 4 1 layer,P5 4 Reserved 5 1 layer, P6 5 Reserved 6 1 layer, P7 6 Reserved 7 1layer, P8 7 Reserved 8 1 layer, P9 8 Reserved 9 1 layer, P10 9 Reserved10 1 layer, P11 10 Reserved 11 1 layer, P12 11 Reserved 12 2 layers,P1-2 12 Reserved 13 2 layers, P3-4 13 Reserved 14 2 layers, P5-6 14Reserved 15 2 layers, P7-8 15 Reserved 16 2 layers, P9-10 16 Reserved 172 layers, P11-12 17 Reserved 18 3 layers, P1-3 18 Reserved 19 3 layers,P4-6 19 Reserved 20 3 layers, P7-9 20 Reserved 21 3 layers, P10-12 21Reserved 22 4 layers, P1-4 22 Reserved 23 4 layers, P5-8 23 Reserved 244 layers, P9-12 24 Reserved 25 Reserved 25 Reserved 26 Reserved 26Reserved 27 Reserved 27 Reserved 28 Reserved 28 Reserved 29 Reserved 29Reserved 30 Reserved 30 Reserved 31 Reserved 31 Reserved

[Table 37] and [Table 38] above separately show 1 codeword (CW)transmission and 2 CW transmission using two columns, but information onthe numbers of antenna ports and transmission layers may be signaledusing only one column as shown in [Table 39] and [able 40]. In [Table39] and [able 40], it is assumed that 2CW transmission is marked but 1CWtransmission is not separately marked.

Specifically, [Table 39] is a form modified from [Table 30] and shows aDMRS table design method when a maximum number of MU-MIMO layerssupported per UE is 2 in the case in which MU-MIMO is supported usingtwelve orthogonal ports based on one column, and [Table 40] is a frommodified from [Table 31] and shows a DMRS table design method when amaximum number of MU-MIMO layers is 4 in the case in which MU-MIMO issupported using twelve orthogonal ports based on one column. Thesignaling methods proposed by [Table 39] and [Table 40] may beconsidered as methods for preventing many reserved indexes which are notused for 2CW in [Table 30] and [Table 31].

TABLE 39 Value Message 0 1 layer, P1 1 1 layer, P2 2 1 layer, P3 3 1layer, P4 4 1 layer, P5 5 1 layer. P6 6 1 layer, P7 7 1 layer, P8 8 1layer, P9 9 1 layer, P10 10 1 layer, P11 11 1 layer, P12 12 2 layers,P1-2 13 2 layers, P3-4 14 2 layers, P5-6 15 2 layers, P7-8 16 2 layers,P9-10 17 2 layers, P1 1-12 18 3 layers, P1-3 19 4 layers, P1-4 20 5layers, P1-5 (2CW) 21 6 layers, P1-6 (2CW) 22 7 layers, P1-7 (2CW) 23 8layers, P1-8 (2CW) 24 Reserved 25 Reserved 26 Reserved 27 Reserved 28Reserved 29 Reserved 30 Reserved 31 Reserved

TABLE 40 Value Message 0 1 layer, P1 1 1 layer, P2 2 1 layer, P3 3 1layer, P4 4 1 layer, P5 5 1 layer, P6 6 1 layer, P7 7 1 layer, P8 8 1layer, P9 9 1 layer, P10 10 1 layer, P11 11 1 layer, P12 12 2 layers,P1-2 13 2 layers, P3-4 14 2 layers, P5-6 15 2 layers, P7-8 16 2 layers,P9-10 17 2 layers, P11-12 18 3 layers, P1-3 19 3 layers, P4-6 20 3layers, P7-9 21 3 layers, P10-12 22 4 layers, P1-4 23 4 layers, P5-8 244 layers, P9-12 25 5 layers, P1-5 (2CW) 26 6 layers, P1-6 (2CW) 27 7layers, P1-7 (2CW) 28 8 layers, P1-8 (2CW) 29 Reserved 30 Reserved 31Reserved

Embodiment 2-8

<Embodiment 2-8> synthetically describes the operations of the UE andthe base station for DMRS pattern type 1 and type 2 on the basis of themethods proposed by <Embodiment 2-5>, <Embodiment 2-6>, and <Embodiment2-7> above.

FIG. 31 illustrates the operations of the base station and the UEaccording to the present embodiment. In a first step, the base stationconfigures information of DMRS pattern type 1 and type 2 through higherlayer in step 3100. Next, if DMRS pattern type 1 is configured in step3110, the process moves to step 3105 and the base station may signalinformation on the number of layers and a port number for type 1 asdescribed in <Embodiment 2-7>. Further, as described in <Embodiment2-6>, DMRS power boosting may be differently configured according to thenumber of configured layers.

Next, it is identified whether the DMRS is configured in the one-symbolpattern or the two-symbol pattern in step 3120, and if the DMRS isconfigured in the one-symbol pattern, configure a DMRS parameter for theone symbol as described in <Embodiment 2-5> in step 3125. If the DMRS isconfigured in the two-symbol pattern, the base station configures a DMSRparameter for the two symbols as described in <Embodiment 2-5> in step3130. Thereafter, the UE identifies information configured to the DMRSin step 3135 and performs channel estimation in step 3160.

If the DMRS pattern is configured as type 2 in step 3110, the sameoperation as the operation in the case in which the DMRS pattern isconfigured as type 1 may be performed. As proposed by <Embodiment 2-5>,the DMRS density may vary depending on DMRS port mapping, and differentantenna port mapping methods may be used according to the DMRS includingone or two symbols depending on the DMRS type. Specifically, in the caseof type 1, parameters configurations in step 3125 and 3130 may bedifferent. In the case of type 2, parameter configurations in step 3145and 3150 may be different.

More specifically, if the type 1 pattern is applied in consideration ofDMRS overhead and channel estimation performance, a pattern 2810 may bepreferred when the DMRS includes one symbol. Further, in the case of thetype 1 pattern, if the DMRS includes two symbols, a pattern 2850 or 2860may be preferred. In the case of type 1, parameter configurations instep 3125 and step 3130 may be different as described in <Embodiment2-5>.

Unlike the above, if the type 2 pattern is applied in consideration ofDMRS overhead and channel estimation performance, a pattern 2910 may bepreferred when the DMRS includes one symbol. Further, in the case of thetype 2 pattern, if the DMRS includes two symbols, a pattern 2930 or 2940may be preferred. In the case of type 2, parameter configurations instep 3145 and step 3150 may be the same as described in <Embodiment2-5>.

To perform the above-described embodiments of the disclosure, atransmitter, a receiver, and a processor of each of the UE and the basestation are illustrated in FIGS. 32 and 33. The method of configuringthe DMRS structure, the method by which the base station generates theDMRS sequence, and the transmission/reception method of the base stationand the UE are described in <Embodiment 2-1> to <Embodiment 2-8>, andeach of the receiver, the processor, and the transmitter of the basestation should be operated according to each embodiment in order toperform the methods.

FIG. 32 is a block diagram illustrating an internal structure of the UEaccording to an embodiment of the disclosure. As illustrated in FIG. 32,the UE of the disclosure may include a UE receiver 3200, a UEtransmitter 3204, and a UE processor 3202. The UE receiver 3200 and theUE transmitter 3204 are commonly called a transceiver in the embodimentof the disclosure. The transceiver may transmit and receive a signalto/from the base station. The signal may include control information anddata. To this end, the transceiver includes an RF transmitter thatup-converts and amplifies a frequency of a transmitted signal, an RFreceiver that low-noise amplifies a received signal and down-convertsthe frequency, and the like. Also, the transceiver may receive a signalthrough a radio channel, output the signal to the UE processor 3202, andtransmit the signal output from the UE processor 3202 via the radiochannel. The UE processor 3202 may control a series of processes suchthat the UE operates according to the above-described embodiments of thedisclosure. For example, the UE receiver 3200 may receive a referencesignal from the base station and the UE processor 3202 may performcontrol to analyze a reference signal application method. Further, theUE transmitter 3204 may transmit a reference signal.

FIG. 33 is a block diagram illustrating an internal structure of thebase station according to an embodiment of the disclosure. Asillustrated in FIG. 33, the base station according to the disclosure mayinclude an base station receiver 3301, an base station transmitter 3305,and an base station processor 3303. The base station receiver 3301 andthe base station transmitter 3305 are commonly called a transceiver inthe embodiment of the disclosure. The transceiver may transmit andreceive a signal to/from the UE. The signal may include controlinformation and data. To this end, the transceiver includes an RFtransmitter that up-converts and amplifies a frequency of a transmittedsignal, an RF receiver that low-noise amplifies a received signal anddown-converts the frequency, and the like. Also, the transceiver mayreceive a signal through a radio channel, output the signal to the basestation processor 3303, and transmit the signal output from the basestation processor 3303 via the radio channel. The base station processor3303 may control a series of processes such that the base stationoperates according to the above-described embodiments of the disclosure.For example, the base station processor 3303 may determine a structureof a reference signal and perform control to generate configurationinformation of a reference signal to be transmitted to the UE. Further,the base station may generate a DMRS sequence on the basis thereof.Thereafter, the base station transmitter 3305 may transmit the referencesignal and the configuration information to the UE and the base stationreceiver 3301 may receive the reference signal.

Third Embodiment

Transmission of an aperiodic channel state information reference signal(CSI-RS) may be used to reduce increasing CSI-RS transmission overheadin order to support transmission a UE-specific beamformed CSI-RS, aplurality of transmission and reception points (TRPs), or operation of aplurality of panels. Meanwhile, in the LTE system, the aperiodic CSI-RSis supported only for wide band transmission. However, in the NR system,it is required to support a narrow band (subband) aperiodic CSI-RS inorder to support various UE bandwidths and efficiently use resources. Tothis end, the disclosure provides a method and an apparatus fordetermining a bandwidth for transmission and measurement of theaperiodic CSI-RS in a wireless communication system.

Embodiment 3-1

Hereinafter, the disclosure relates to a method oftransmitting/receiving channel status information by which the UEmeasures a radio channel status (channel quality) and informs the basestation of a measurement result in a wireless mobile communicationsystem applying a multi-access scheme using a multi-carrier, such asorthogonal frequency division multiple access (OFDMA).

In a detailed description of embodiments of the disclosure, anOFDM-based wireless communication system, particularly, 3GPP EUTRAstandard will be mainly described, but the main subject of thedisclosure can be slightly modified without departing from the scope ofthe disclosure in other communication systems having similar technicalbackground and channel form.

FIG. 34 illustrates an FD-MIMO system to which an embodiment of thedisclosure is applied. The FD-MIMO system introduced to LTE-A Pro isevolved from the conventional LTE and LTE-A MIMO technology and may usemultiple transmission antennas larger than or equal to 8 antennas. InFIG. 34, an eNB transmission device 3400 transmits a wireless signal to8 or more transmission antennas. A plurality of transmission antennasmay be disposed to maintain a minimum distance therebetween as indicatedby reference numeral 3410. For example, the minimum distance may be halfthe wavelength of the wireless signal. In general, if the distancecorresponding to half the wavelength of the wireless signal ismaintained between the transmission antennas, a signal transmitted fromeach transmission antenna is influenced by a wireless channel having lowcorrelation. If a bandwidth of the transmitted wireless signal is 2 GHz,the distance may be 7.5 cm, and if the band becomes higher than 2 GHz,the distance becomes shorter.

In FIG. 34, 8 or more transmission antennas arranged in an eNBtransmission device 3400 may be used to transmit signals to one or aplurality of UEs as indicated by reference numeral 3420. Appropriateprecoding is applied to a plurality of transmission antennas and signalsare simultaneously transmitted to a plurality of UEs. At this time, oneUE may receive one or more of information streams. In general, thenumber of information streams which one UE can receive is determinedaccording to the number of reception antennas which the UE occupies anda channel condition.

FIG. 35 illustrates radio resources corresponding to one subframe andone resource block (RB) which are minimum units that can be scheduled tothe downlink in the LTE and LTE-A systems. The radio resourcesillustrated in FIG. 35 consists of one subframe on the time axis and oneRB on the frequency axis. The radio resources include 12 subcarriers inthe frequency region and 14 OFDM symbols in the time region and thushave a total of 168 inherent frequency and time locations. In LTE andLTE-A, each of the inherent frequency and time locations in FIG. 35 maybe referred to as a resource element (RE).

In the radio resources illustrated in FIG. 35, a plurality of differenttypes of signals below may be transmitted.

1. Cell specific RS (CRS) 3500: refers to a reference signalperiodically transmitted for all UEs belonging to one cell and may beused by a plurality of UEs in common.

2. Demodulation reference signal (DMRS) 3510: refers to a referencesignal transmitted for a specific UE and is transmitted only when datais transmitted to the corresponding UE. The DMRS may consist of a totalof 8 DMRS ports. In LTE-A, port 7 to port 14 correspond to DMRS ports,and each port maintain orthogonality to prevent interference throughcode division multiplexing (CDM) or frequency division multiplexing(FDM).

3. Physical downlink shared channel (PDSCH) 3520: refers to a datachannel transmitted to downlink, and is used when the base stationtransmits traffic to the UE and transmitted using an RE through which areference signal is not transmitted in a data region 3560.

4. Channel status information reference signal (CSI-RS) 3540: refers toa reference signal transmitted for UEs belonging to one cell and is usedto measure a channel status. A plurality of CSI-RSs may be transmittedin one cell. In the LTE-A system, one CSI-RS may correspond to one, two,four, or eight antenna ports (APs) (or interchangeably used with ports).In the LTE-A Pro system, one CSI-RS may correspond to one, two, four,eight, twelve, or sixteen antenna ports and may be extended to a maximumof thirty antenna ports in the future.

5. Other channels (a physical hybrid-ARQ indicator channel (PHICH), aphysical control format indicator channel (PCFICH), and a physicaldownlink control channel (PDCCH)) 3530: used when the UE providescontrol information required for receiving a PDSCH or to transmitACK/NACK for operating HARQ of uplink data transmission. The controlchannels are transmitted in a control region 3550.

In addition to the above signals, in order to allow the CSI-RS whichanother base station transmits to be received by UEs in thecorresponding cell, muting may be set in the LTE-A and LTE-A Prosystems. Muting may be applied to a location where the CSI-RS may betransmitted, and generally, the UE may skip the corresponding radioresources and receive a traffic signal. In the LTE-A and LTE-A Prosystems, the muting may be referred to as a zero-power CSI-RS as adifferent term. This is because muting is equally applied to thelocation of the CSI-RS and transmission power is not transmitted due toa muting characteristic.

In FIG. 35, CSI-RSs may be transmitted using some of the locationsmarked by A, B, C, D, E, F, G, H, I, and J according to the number ofantennas for transmitting the CSI-RSs. In addition, the muting may alsobe applied to some of the locations marked with A, B, C, D, E, F, G, H,I, and J. Particularly, CSI-RSs may be transmitted using two, four, oreight REs according to the number of transmission antenna ports. ACSI-RS is transmitted to half of a particular pattern in FIG. 35 if thenumber of antenna ports is 2, a CSI-RS is transmitted to the entirety ofa particular pattern if the number of antenna ports is 4, and a CSI-RSis transmitted using two patterns if the number of antenna ports is 8.In contrast, the muting is always applied in units of one pattern. Thatis, muting may be applied to a plurality of patterns but may not beapplied only to some of a single pattern when the location does notoverlap the CSI-RS. However, only when the locations of the CSI-RS andthe muting overlap each other, the muting may be applied only to aportion of one pattern.

As described above, in LTE-A, two, four, or eight antenna ports may beconfigured in one CSI-RS resource. If CSI-RSs for two antenna ports aretransmitted, the signal of each antenna port is transmitted in two REscontiguous on the time axis, and the signals of the antenna ports may bedistinguished by orthogonal code. Further, if CSI-RSs for four antennaports are transmitted, in additional to the CSI-RSs for the two antennaports, signals for the remaining two antenna ports are transmitted inthe same way as the above by using additional two REs. In the samemanner, the transmission of CSI-RSs for eight antenna ports may beexecuted.

The base station may boost CSI-RS transmission power in order to improvechannel estimation accuracy. If four or eight antenna port CSI-RSs aretransmitted, a specific CSI-RS port may be transmitted only in a CSI-RSRE at a predetermined location and may not be transmitted in anotherOFDM symbol within the same OFDM symbol. FIG. 36 illustrates an exampleof CSI-RS RE mapping for n^(th) and n+1^(th) PRBs in the case in whichthe base station transmits CSI-RSs of eight antenna ports. Asillustrated in FIG. 36, if the CSI-RS RE location for a 15^(th) or16^(th) AP is as indicated by reference numeral 3600 (secondsubcarrier), no transmission power is used in CSI-RS REs 3610 (third,eighth, and ninth subcarriers) for the remaining 17^(th) to 22^(nd) APslike the 15^(th) or 16^(th) AP. Accordingly, in a second subcarrier, the15^(th) or 16^(th) AP may use transmission power to be used in third,eighth, and ninth subcarriers.

The natural power boosting can be configured such that power of the15^(th) CSI-RS port transmitted through the second subcarrier is higherby a maximum of 6 dB than transmission power used in a data RE 3620. Thecurrent 2^(nd)/4^(th)/8^(th) port CSI-RS patterns may perform naturalpower boosting of 0/2/6 dB, and each AP may transmit the CSI-RS withfull power utilization.

Further, the UE may receive allocation of CSI-IM (or interferencemeasurement resource (IMR)) together with the CSI-RS, and CSI-IMresources have the same structure and location as the CSI-RS supporting4 ports. The CSI-IM corresponds to resources for accurately measuringinterference from adjacent base stations by the UE receiving data fromone or more base station. If the base station desires to measure anamount of interference when the adjacent base station transmits data andan amount of interference when the adjacent base station does nottransmit data, the base station may configure the CSI-RS and two CSI-IMresources to effectively measure the amounts of interference from theadjacent base station by allowing the adjacent base station to alwaystransmit a signal in one CSI-IM and allowing the adjacent base stationto not always transmit a signal in the other CSI-IM.

In the LTE-A and LTE-A Pro systems, the base station may notify the UEof CSI-RS resource configuration information (or CSI-RS resourceconfiguration) through higher layer signaling. The CSI-RS resourceconfiguration information includes an index of the CSI-RS configurationinformation, the number of ports included in the CSI-RS, a transmissionperiod of the CSI-RS, a transmission offset, CSI0RS configurationinformation (CSI-RS configuration), a CSI-RS scrambling ID, and quasico-location (QCL) information. Specifically, the UE may determine REs inwhich the CSI-RS is transmitted by combining the CSI-RS configurationinformation and information on the number of ports included in theCSI-RS.

In the LTE-A and LTE-A Pro systems, the base station transmits areference signal to the UE in order to measure a downlink channel stateand the UE measures a channel state between the base station and the UEthrough the CRS or the CSI-RS which the base station transmits. Inassociation with the channel state, several factors need to be basicallyconsidered, and the amount of interference in downlink may be includedtherein. The amount of interference in downlink may include aninterference signal generated by an antenna that belongs to aneighboring base station, a thermal noise, and the like, which isimportant when a UE determines the channel status of the downlink.

For example, if the base station having one transmission antennatransmits a signal to the UE having one reception antenna, the UE maydetermine energy per symbol which can be received through downlink onthe basis of the reference signal received from the base station andamounts of interference to be simultaneously received in an interval inwhich the corresponding symbol is received and may determine Es/Io(energy per symbol-to-interference ratio). The determined Es/Io isconverted to a data transmission rate or a value corresponding theretoand transmitted to the base station in a form of channel qualityindicator (CQI), and thus the base station may determine a datatransmission rate at which the base station performs transmission to theUE in the downlink.

In LTE-A and LTE-A Pro systems, the UE transmits feedback of informationon a downlink channel status to the base station to allow the basestation to use the received information for scheduling. That is, the UEmeasures a reference signal which the base station transmits through thedownlink and transmits feedback of information extracted therefrom tothe base station in a form defined by the LTE/LTE-A standard. In LTE andLTE-A systems, information fed back by the UE largely includes threepieces of information below.

-   -   Rank indicator (RI): a number of spatial layers which the UE can        receive in a current channel status    -   Precoder matrix indicator (PMI): an indicator of a precoding        matrix which the UE prefers in a current channel status    -   Channel quality indicator (CQI): a maximum data rate at which        the UE can perform reception in a current channel status The CQI        may be replaced with an SINR, a maximum error correction code        rate, a modulation scheme, data efficiency per frequency, and        the like, which may be utilized to be similar to the maximum        data rate.

The RI, PMI, and CQI are interrelated. For example, precoding matrixessupported by LTE and LTE-A systems are differently defined for eachrank.

Accordingly, even though values of the PMI when the RI is 1 and thevalue of the PMI when the RI is 2 are the same as each other, they areinterpreted differently. Further, when the UE determines CQI, the UEassumes that a rank value and a PMI value, which the UE provides to thebase station, are applied to the base station. That is, if the UEprovides RI_X, PMI_Y, and CQI_Z to the base station, it means that theUE can perform reception at a data transmission rate corresponding toCQI_Z when the rank is RI_X and the precoding is PMI_Y. As describedabove, when the UE calculates CQI, the UE considers which transmissionscheme is used for the base station and thus acquire optimal performancewhen actual transmission is performed using the correspondingtransmission scheme.

The RI, the PMI, and the CQI may be fed back periodically oraperiodically. If the base station desires to obtain aperiodic feedbackinformation of a specific UE, the base station may configure anaperiodic feedback indicator included in downlink control information(DCI) for uplink data scheduling of the corresponding UE to executespecific aperiodic feedback, and perform uplink data scheduling of thecorresponding UE. If the UE receive the indicator configured to executeaperiodic feedback in an n^(th) subframe, the UE performs uplinktransmission by inserting aperiodic feedback information into datatransmission in an n+k^(th) subframe. Here, k is 4 in frequency divisionduplexing (FDD) and is defined as shown in [Table 41] in time divisionduplexing (TDD).

TABLE 41 TDD UL/DL Config- subframe number n uration 0 1 2 3 4 5 6 7 8 90 — — 6 7 4 — — 6 7 4 1 — — 6 4 — — — 6 4 — 2 — — 4 — — — — 4 — — 3 — —4 4 4 — — — — — 4 — — 4 4 — — — — — — 5 — — 4 — — — — — — — 6 — — 7 7 5— — 7 7 —

In order to generate and report the channel information, the basestation having massive antennas is required to configure referencesignal resources for measuring channels of 8 or more antennas andtransmit the reference signal resources to the UE. To this end, in theLTE-A Pro system, two, four, eight, twelve, or sixteen antenna ports maybe configured in one CSI-RS resource, and a function for configuringtwenty, twenty two, twenty eight, and thirty two antenna ports may beadded in the future. Specifically, in LTE-A Pro release-13, two types ofCSI-RS configuration methods are provided.

In a first method, the base station configures one or more 4- or 8-portCSI-RS patterns in the UE through a non-precoded (NP) CSI-RS (CSI-RS forreporting class A channel state information (CSI)) and combine acombination of the configured CSI-RS patterns so as to allow the UE toreceive CSI-RSs according to 8 or more CSI-RS ports. Specifically, a {1,2, 4, 8}-port CSI-RS follows the conventional mapping rule. Aggregationof three 4-port CSI-RS patterns is configured in the case of a 12-portCSI-RS, and aggregation of two 8-port CSI-RS patterns may be configuredin the case of a 16-port CSI-RS. Further, in LTE-A release-13, codedivision multiplexing (CDM)-2 or CDM-4 is supported using orthogonalcover code (OCC) having a length of 2 or 4 for the 12-116-port CSI-RS.

The description of FIG. 36 is about CSI-RS power boosting based onCDM-2, and a maximum of 9 dB of power boosting compared to a PDSCH isneeded for full power utilization for the 12-116-port CSI-RS based onCDM-2 according to the description. This means that higher-performancehardware is required for full power utilization in the operation of the12-/16-port CSI-RS based on CDM-2. In LTE-A Pro release-13, the12-/16-port CSI-RS based on CDM-4 is introduced in considerationthereof, in which case full power utilization is possible through powerboosting of 6 dB which is the same as the conventional power boosting.

In a second method, the base station may apply a specific beam to aplurality of transceiver units (TXRUs) through a beamformed (BF) CSI-RS(CSI-RS for reporting Class B CSI) to allow the UE to recognize theplurality of TXRUs as one CSI-RS port. If the base station knows UEchannel information in advance, the base station may configure only afew of CSI-RSs to which a beam suitable for the channel information isapplied in its own TXRU. In another example, the base station mayconfigure a plurality of CSI-RS resources including 8 or fewer CSI-RSports in the UE. At this time, the base station may apply differentdirection of beams for each CSI-RS resource configuration to beamformthe CSI-RS ports.

FIG. 37 illustrates an example of BF CSI-RS operation. Referring to FIG.37, an base station 3710 may configure three CSI-RSs 3720, 3730, and3740, which are beamformed in different directions, in UEs 3750 and3760. Each of the CSI-RS resources 3720, 3730, and 3740 may include oneor more CSI-RS ports. A UE 3750 may generate channel state informationfor the configured CSI-RS resources 3720, 3730, and 3740 and report anindex of CSI-RS resources which the UE prefers among the CSI-RSresources to the base station through a CSI-RS resource indicator (CRI).In the example of FIG. 37, if the UE 3750 prefers the CSI-RS resources3730, the UE may report an index corresponding to the CSI-RS resource3730 to the base station. If the UE 3760 prefers CSI-RS resources 3720,the UE may report an index corresponding to the CSI-RS resources 3720 tothe base station.

The CRI supports a report on one CSI-RS index which the UE most prefersbased on LTE-A Pro release-13, but may be extended to a combination ofCSI-RS indexes which the UE prefers in the future. For example, if twoCSI-RS resources which the UE 3750 most prefers are CSI-RS resources3730 and 3740, the UE 3750 may directly report two indexes of thecorresponding CSI-RS resources or report an index indicating a set ofthe corresponding CSI-RS resources. This is to allow variousapplications by supporting a UE having wide angular spread of a channelor having high mobility with beams in various directions or supportingselection of a plurality of CSI-RSs transmitted in differenttransmission and reception points (TRPs).

Embodiment 3-2

<Embodiment 3-2> proposes a method of configuring an aperiodic CSI-RS.Up to LTE-A Pro release-13, detailed configuration values of the CSI-RSare semi-statically determined by higher layer signaling (or RRCsignaling) as described in <Embodiment 3-1>. CSI-RS resourceconfiguration information up to LTE-A Pro release-13 includes thefollowing information.

-   -   The number of CSI-RS ports: indicates the number of CSI-RS ports        included in one CSI-RS resource.    -   CSI-RS configuration: indicates a configuration value indicating        locations of CSI-RS REs together with the number of CSI-RS        ports.    -   CSI-RS subframe configuration, I_(CSI-RS): indicate        configuration values indicating a CSI-RS transmission period, a        T_(CSI-RS), a CSI-RS subframe offset, and Δ_(CSI-RS).    -   CSI-RS power boosting factor, P_(C): assumes a UE for ratio of        CSI-RS transmission power to a PDSCH.    -   Scrambling ID, n_(ID)    -   Quasi co-location (QCL) information

The conventional CSI-RS is periodically transmitted, including thedetermined number of ports according to the determined detailedconfiguration values. Accordingly, if it is assumed that UE-specificbeamforming is applied to the beamformed CSI-RS, CSI-RS resourceconfigurations corresponding to the number of UEs are needed, which maybe a big burden. Alternatively, if cell-specific beamforming is appliedto the beamformed CSI-RS, the number of antennas of the base stationalso increases, and thus if a beam width becomes narrower, many CSI-RSresource configurations are needed as well.

In order to solve the problem and enable efficient CSI-RS resourceallocation, it is possible to introduce aperiodic CSI-RS (Ap-CSI-RS)transmission. In a viewpoint of one UE, the aperiodic CSI-RS is notalways transmitted in all the configured resources but is transmittedonly in resources satisfying a particular condition.

FIG. 38 illustrates an example of CSI-RS transmission/reception and aCSI report according thereto. Referring to FIG. 38, the base station mayconfigure CSI-RS resources for aperiodic CSI-RS transmission in each UEas indicated by reference numeral 3800. At this time, the base stationmay configure the same aperiodic CSI-RS resources in a plurality of UEsin consideration of information indicating that the aperiodic CSI-RS isnot always transmitted. This is to increase efficiency of the use ofCSI-RS resources by operating an aperiodic CSI-RS resource pool sharedbetween a predetermined number of UEs.

The base station may trigger the aperiodic CSI report to the UE throughL1 signaling such as UL grant on the basis of the CSI-RS configurationinformation as indicated by reference numeral 3810. The UE can performthe following operation according to an aperiodic CSI-RS configurationmethod based on the aperiodic CSI triggering.

1. Method of receiving aperiodic CSI-RS transmitted in a subframe whichis the same as that in which the aperiodic CSI triggering istransmitted.

2. Method of receiving the aperiodic CSI-RS transmitted in a subframewhich is the closest to the subframe in which the aperiodic CSItriggering is signaled.

3. Method of receiving the aperiodic CSI-RS transmitted in a subframewhich is the closest to a subframe after the subframe in which theaperiodic CSI triggering is signaled.

4. Method of receiving the aperiodic CSI-RS transmitted after apredetermined time from the subframe in which the aperiodic CSItriggering is signaled, for example, after an l^(th) subframe, wherein lmay be configured to be smaller than k described above. Further, l maybe a predetermined value or a value designated by higher layer signalingor L1 signaling.

Thereafter, the UE may generate CSI on the basis of the receivedaperiodic CSI-RS and report the CSI to the base station in the n+k^(th)subframe as described above as indicated by reference numerals 3820 and3830. Here, the n^(th) subframe is a subframe including the aperiodicCSI trigger. If the UE follows “4. The method of receiving the aperiodicCSI-RS transmitted after a predetermined time from the subframe in whichthe aperiodic CSI triggering is signaled, for example, after an l^(th)subframe, wherein 1 may be configured to be smaller than k describedabove”, the CSI generated by the UE may be reported to the base stationin an n+k+l^(th) subframe. This is to secure a UE processing time forthe CSI generation.

A detailed method of operating the aperiodic CSI-RS resource pool isdescribed below.

1. Method of using RRC signaling+L1 signaling

2. Method of using RRC signaling+MAC CE signaling+L1 signaling

3. Method of using RRC signaling+MAC CE signaling

The RRC signaling, the MAC CE signaling, and the L1 signaling havehigher reliability in the order of RRC>MAC CE>L1 in terms of reliabilityand require a delay time in the order of L1<MAC CE<RRC in terms ofdelay. For example, when the UE receives the information, theinformation configured through the RRC signaling has high reliabilitybut requires a long time for reception, and the information configuredthrough the L1 signaling has a very short delay time required forreception but relatively low reliability. Further, the L1 signaling hasa disadvantage of high signaling costs due to transmission by limitedDCI.

As described in the first example, if the method of 1. RRC signaling+L1signaling is used, the base station may configure N CSI-RS resources inthe UE through RRC signaling and then select L (<N) resources from amongthe N configured CSI-RS resources through L1 signaling. At this time,since L1 signaling overhead is determined by N and L (N combination L,NCL), if N=8 CSI-RS resources are configured through RRC and L≤2resources are selected through L1 signaling, very large DCI payloadcorresponding to a total of ┌log₂(28+8)┐=6 bits may be needed.

Meanwhile, as described in the second example, if the method of 2. RRCsignaling+MAC CE signaling+L signaling is used, specific CSI-RSresources designated through MAC CE signaling among the RRC-signaledCSI-RS resources may be activated or deactivated and L signaling may beperformed therefor. Accordingly, the base station may acquire propertradeoff between the CSI-RS resource configuration delay time and theDCI signaling overhead. For example, if N=8 CSI-RS resources areconfigured through RRC, K=4 resources among the N=8 CSI-RS resources areactivated through the MAC CE, and then L≤2 resources are selectedthrough L signaling, it is noted that required DCI payload may bereduced to a total of ┌log₂(6+4)┐=4 bits compared to the first example.

As described in the third example, if the method of 3. RRC signaling+MACCE signaling is used, K CSI-RS resources designated through MAC CEsignaling among the RRC-signaled N CSI-RS resources may be activated ordeactivated. At this time, unlike the first and second examples, the UEfinally determines whether to transmit the CSI-RS through the MAC CEwithout L1 signaling. In this case, CSI-RS aperiodic transmissionindication for every subframe is not possible, but there is an advantageof significantly reduced DCI overhead.

In the present embodiment, the aperiodic CSI-RS can be configuredthrough higher layer signaling. CSI-RS resource configurationinformation for the aperiodic CSI-RS may include detailed configurationinformation such as the number of CSI-RS ports, CSI-RS configuration,CSI-RS subframe configuration, the CSI-RS power boosting index, thescrambling ID, and quasi co-location (QCL) information as describedabove. If CSI-RS resource configuration information for the aperiodicCSI-RS includes the CSI-RS subframe among the detailed configurationinformation, “2. The method of receiving the aperiodic CSI-RStransmitted in a subframe which is the closest to the subframe in whichthe aperiodic CSI triggering is signaled” or “3. The method of receivingthe aperiodic CSI-RS transmitted in a subframe which is the closest to asubframe after the subframe in which the aperiodic CSI triggering issignaled” may be used among the aforementioned aperiodic CSI-RSreception methods. This is because the CSI-RS subframe configurationincludes information on candidate subframes in which the aperiodicCSI-RS can be transmitted.

Meanwhile, if CSI-RS resource configuration information for theaperiodic CSI-RS does not include the CSI-RS subframe configurationamong the detailed configuration information or if, even though theCSI-RS resource configuration information includes the CSI-RS subframeconfiguration, ignorance thereof is appointed (or indicated by the basestation), the CSI-RS resource configuration information may not includeinformation on candidate subframes in which the aperiodic CSI-RS can betransmitted. Accordingly, among the aforementioned aperiodic CSI-RSreception methods, “1. The method of receiving aperiodic CSI-RStransmitted in a subframe which is the same as that in which theaperiodic CSI triggering is transmitted” or “4. The method of receivingthe aperiodic CSI-RS transmitted after a predetermined time from thesubframe in which the aperiodic CSI triggering is signaled, for example,after an 1^(th) subframe” may be used.

In L1 signaling (UL, DCI, or UL grant), aperiodic CSI-RS triggeringincluding 1 bit or a plurality of bits may exist. If 1-bit aperiodicCSI-RS triggering is supported through L1 signaling, a method ofanalyzing a CSI request field of DCI format 0 or DCI format 4 may varydepending on whether triggering is performed. The DCI format is only anexample, and a DCI format for uplink grant such as DCI format 0 or 4 maycorrespond thereto. For example, if the aperiodic CSI-RS is nottriggered, the CSI request field may serve to indicate a set to reportthe CSI among a set of serving cells configured by a higher layer, a setof CSI processes, or a set of CSI subframes like in the prior art. Onthe other hand, if the aperiodic CSI-RS is triggered, the CSI requestfield may serve to indicate CSI-RS resources in which the aperiodicCSI-RS is transmitted among a plurality of CSI-RS resource candidates asshown in [Table 42]. At this time, since the aperiodic CSI-RStransmission is triggered through additional 1-bit L1 signaling, allcode points of the CSI request field may have another meaning other than“no aperiodic CSI-RS and aperiodic CSI are triggered”.

In another example, if 1-bit aperiodic CSI-RS triggering is supported,the method of analyzing the CSI request field of DCI format 1 or DCIformat 4 may be indicated by higher layer signaling (RRC signaling). Inthis case, the CSI request field may serve to indicate a set to reportthe CSI among a set of serving cells configured through the higherlayer, a set of CSI processes, or a set of CSI subframes like in theprior art or serve to indicate CSI-RS resources in which the aperiodicCSI-RS is transmitted among a plurality of CSI-RS resource candidates asdescribed in the example of [Table 43]. At this time, since the CSIrequest field should include a function for triggering the aperiodicCSI-RS, at least one code point may have a meaning indicating that “noaperiodic CSI-RS and aperiodic CSI are triggered”

TABLE 42 Value of CSI request field Description 00 Aperiodic CSI-RS andaperiodic CSI report are triggered for a set of CSI-RS resourcesconfigured by higher layers for serving cell c 01 Aperiodic CSI-RS andaperiodic CSI report are triggered for a 1st set of CSI-RS resourcesconfigured by higher layers 10 Aperiodic CSI-RS and aperiodic CSI reportare triggered for a 2nd set of CSI-RS resources configured by higherlayers 11 Aperiodic CSI-RS and aperiodic CSI report are triggered for a3rd set of CSI-RS resources configured by higher layers

TABLE 43 Value of CSI request field Description 00 No aperiodic CSI-RSand aperiodic CSI reporting are triggered 01 Aperiodic CSI-RS andaperiodic CSI report are triggered for a set of CSI-RS resourcesconfigured by higher layers for serving cell c 10 Aperiodic CSI-RS andaperiodic CSI report are triggered for a 1st set of CSI-RS resourcesconfigured by higher lavers 11 Aperiodic CSI-RS and aperiodic CSI reportare triggered for a 2nd set of CSI-RS resources configured by higherlayers

On the other hand, aperiodic CSI-RS triggering including a plurality ofbits may include a function of indicating which CSI-RS resources areused to transmit the aperiodic CSI-RS. [Table 44] shows an example of anaperiodic CSI-RS triggering field including two bits. According to theexample of [Table 44], at least one code point in the aperiodic CSI-RStriggering field may have a meaning indicating that “no aperiodic CSI-RSand aperiodic CSI are triggered”. Other three code points meansaperiodic CSI-RS triggering (01) in a serving cell c, and aperiodicCSI-RS triggering (10, 11) for first and second CSI-RS sets higherlayer-signaled for a plurality of serving cells (across serving cells).At this time, the CSI-RSs are associated with different aperiodicCSI-RSs and aperiodic CSI reports. Even when the aperiodic CSItriggering field includes three or more bits, extension is possible onthe basis of a principle similar to [Table 44]. A new table like [Table44] may be designated by a new transmission mode (TM), for example, TM11.

TABLE 44 Value of aperiodic CSI-RS field Description 00 No aperiodicCSI-RS and aperiodic CSI reporting are triggered 01 Aperiodic CSI-RS andaperiodic CSI report are triggered for a set of CSI-RS resourcesconfigured by higher layers for serving cell c 10 Aperiodic CSI-RS andaperiodic CSI report are triggered for a 1st set of CSI-RS resourcesconfigured by higher layers 11 Aperiodic CSI-RS and aperiodic CSI reportare triggered for a 2nd set of CSI-RS resources configured by higherlayers

Embodiment 3-3

The present embodiment describes an example of dynamic port numberingconfiguration in the method of configuring the aperiodic CSI-RS. Dynamicport numbering means that the number of CSI-RS ports included inaperiodic CSI-RS resources may be different when the aperiodic CSI-RS istransmitted. For example, this means that the aperiodic CSI-RS resourcesmay be configured by dynamic CSI-RS resource aggregation.

FIG. 39 illustrates an example of a dynamic port numbering operationscenario for the aperiodic CSI-RS. In FIG. 39, it is assumed that eachof base stations 3900 and 3905 operates eight CSI-RS ports.

For example, if a UE 3910 receives data from the base station 3900, thebase station 3900 may transmit the aperiodic CSI-RS and triggeraperiodic CSI in a subframe 3915 through 11 signaling. The UE 3910 mayreceive the aperiodic CSI-RS transmitted in aperiodic CSI-RS resources3925 through a method similar to <Embodiment 3-2>, generate CSI for achannel 3920 including 8-port CSI-RSs, and reports the same to the basestation.

In another example, if the UE 3910 simultaneously receives data from thebase stations 3900 and 3905 (for example, like in CoMP JT), the basestation may transmit the aperiodic CSI-RS and trigger the aperiodic CSIin a subframe 3930 through L1 signaling. At this time, aperiodic CSI-RStriggering may mean that aperiodic CSI-RS resources 3940 for measuring achannel 3935 and aperiodic CSI-RS resources 3950 for measuring a channel3945 are simultaneously transmitted. Although FIG. 29 illustrates thesituation in which the CSI-RS resources 3940 and 3950 are configured indifferent subframes for convenience of description, the disclosure isnot limited thereto and the CSI-RS resources may be transmitted in thesame subframe according to the aperiodic CSI-RS triggering method in<Embodiment 3-2>.

The UE may receive the aperiodic CSI-RSs 3940 and 3950 and generate andreport CSI based on the 8-port CSI-RSs for each CSI-RS resource (use 8Txcodebook), but may recognize the CSI-RSs 3940 and 3950 as one CSI-RSresource (aggregation between aperiodic CSI-RS resources) and generateand report CSI based on 16-port CSI-RSs (use 16Tx codebook). This is toallow the UE to generate a PMI using a codebook larger than the numberof antennas, and the generated PMI includes not only a phase betweenbase station antennas but also implicitly a phase difference between theTRP 3900 and TRP 3905, so that a CQI mismatch problem in coordinatedmultipoint (CoMP) joint transmission (JT) may be solved.

FIG. 40 illustrates another example of the dynamic port numberingoperation scenario for the aperiodic CSI-RS. In the future, the CSI maybe extended to have a function for indicating a plurality of preferredCSI-RS sources or one subset including a plurality of CSI-RS resources.If a total sum of the numbers of CSI-RS ports of CSI-RS resourcesincluded in one subset is different, it may be required to apply adifferent precoding scheme according to the selected CSI-RS resourcesubset.

For example, a “one cell” operation scenario as illustrated in FIG. 40is assumed. At this time, a coverage RS (CRS, coverage CSI-RS, orcell-specific CSI-RS) is transmitted by a macro base station 4000, but aUE-specific RS 4030, 4040, 4050, or 4060 (CSI-RS, UE-specific CSI-RS, ordedicated CSI-RS) may be transmitted in a different TRP. That is,respective TRPs may be distinguished by a UE-specific RS. When it isassumed that each TRP has a plurality of UE-specific RS resources towhich different beams are applied, the UE may report preferredUE-specific RS resource information for each TRP to the base stationthrough CRI. For example, when it is assumed that the UE receives datain a plurality of TRPs, if data is received in TRPs 4010 and 4020, theUE may report one preferred CSI-RS among CSI-RSs 4030 and 4040 for theTRP 4010 and one preferred CSI-RS among CSI-RSs 4050 and 4060 for theTRP 4020. In this case, the base station may selectively transmit theaperiodic CSI-RS in a plurality of CSI-RS resources with reference to UEpreference. As described above, if the aperiodic CSI-RS is transmittedin a plurality of CSI-RS resources, a detailed configuration andtransmission method may be similar to the example of FIG. 39.

Specifically, the following methods may be considered for dynamic portconfiguration-based or dynamic resource aggregation-based aperiodicCSI-RS configuration.

-   -   Aperiodic CSI-RS configuration method 1

A first method is aperiodic CSI-RS configuration through higher layersignaling and 1-bit L1 signaling. In the example, higher layer-signaledCSI-RS resource configuration information for the aperiodic CSI-RS is asillustrated in FIG. 41.

FIG. 41 illustrates an example of CSI-RS resource configurationinformation. Referring to FIG. 41, three types of higher layer signalingcan be performed in consideration of CSI-RS types such as a non-precodedCSI-RS, a beamformed CSI-RS, and a hybrid CSI-RS. At this time, higherlayer signaling may include RRC signaling and MAC CE signaling asdescribed in <Embodiment 3-2>. This means that CSI-RS resources orconfigurations indicated by K_(A), K_(B), K_(CA), or K_(CB) in FIG. 41may depend on only RRC configuration but may be activated or deactivatedthrough MAC CE configuration. Although FIG. 41 mainly illustrates RRCconfiguration, it may be extended to aggregation of RRC and MAC CEsimilarly to description of <Embodiment 3-2>, so a detailed descriptionthereof will be omitted.

In the case of the non-precoded CSI-RS, higher layer signaling mayinclude signaling information 4120. Specifically, the signalinginformation 4120 includes A CSI-RS configurations 4130 for configuring aplurality of CSI-RS ports larger than or equal to 8 CSI-RS ports andanother detailed configuration information 4140. At this time, if theaperiodic CSI-RS is triggered through 1-bit L1 signaling, this may meanthat the aperiodic CSI-RS is transmitted in all CSI-RS REs designated byreference numeral 4130.

In the case of the beamformed CSI-RS, higher layer signaling may includesignaling information 4150. Specifically, the signaling information 4150may include K_(B) CSI-RS resource configuration information to whichdifferent beams can be applied, and CSI-RS resource configurationinformation 4160 may include CSI-RS detailed configuration information.At this time, if the aperiodic CSI-RS is triggered through 1-bit L1signaling, two methods below may be considered.

A first method is to transmit the aperiodic CSI-RS in all CSI-RS REsdesignated by reference numeral 4160. In this case, a CRI can bereported through the aperiodic CSI-RS, but an effect of reduction inCSI-RS overhead due to the aperiodic CSI-RS may be reduced. A secondmethod is to transmit the aperiodic CSI-RS only in CSI-RS resourcesdesignated by the CRI reported by the UE among the information 4160. Inthis case, the effect of reduction in CSI-RS overhead may be maximizedbut it is difficult to perform the CRI report through the aperiodicCSI-RS. In the second method, if the CRI designates a plurality ofCSI-RS resources, the designated CSI-RS resources may be recognized as asingle CSI-RS resource. For example, if the CRI designates two 8-portCSI-RS resources as aperiodic CSI-RS resources, the number of aperiodicCSI-RS ports assumed by the UE is a sum of the numbers of CSI-RS portsincluded in the two CSI-RS resources, that is, 16.

In the case of the hybrid CSI-RS, higher layer signaling may includesignaling information 4170. Specifically, the signaling information 4170may include two parts such as a part 4180 including K_(CA) CSI-RSconfigurations for configuring a plurality of CSI-RS ports and a part4190 including K_(CB) pieces of CSI-RS resource configurationinformation to which different beams can be applied. For example, thepart 4180 may be similar to reference numeral 4120, and the part 4190may be similar to reference numeral 4150. At this time, if the aperiodicCSI-RS is triggered through 1-bit L1 signaling, two methods below may beconsidered.

A first method is to transmit the aperiodic CSI-RS in all CSI-RS REsdesignated by reference numeral 4180. In this case, CSI-RS portsdesignated by reference numeral 4190 are transmitted periodic CSI-RSresources. A second method is to transmit the aperiodic CSI-RS only in apart designated by CRI among all CSI-RS REs designated by referencenumeral 4190 or all CSI-RS resources designated by reference numeral4190. In the case of the hybrid CSI-RS, aperiodic CSI-RS triggeringthrough 2-bit L1 signaling may be supported. For example, the respectivebits may be used to indicate whether the aperiodic CSI-RS is transmittedin CSI-RS resources designated by reference numeral 4180 and indicatewhether the aperiodic CSI-RS is transmitted in CSI-RS resourcesdesignated by reference numeral 4190.

In this example, if L1 signaling for aperiodic CSI-RS triggering isapplied to “all CSI-RS resources”, the L1 signaling may be individuallysupported for each CSI process. Alternatively, if L1 signaling foraperiodic CSI-RS triggering is applied to “CSI-RS resources designatedby the CRI”, the L signaling may be applied to the corresponding CSI-RSresources regardless of the CSI process.

-   -   Aperiodic CSI-RS configuration method 2

The second method corresponds to aperiodic CSI-RS configuration throughhigher layer signaling and L signaling including a plurality of bits. Inthis example, CSI-RS resource configuration information higherlayer-signaled for the aperiodic CSI-RS is as illustrated in FIG. 42.

FIG. 42 illustrates another example of CSI-RS resource configurationinformation. Since configurations of FIG. 42 are the same as or similarto those of FIG. 41 except for the configuration 4220, FIG. 42 may referto reference numerals of FIG. 41. At this time, higher layer signalingmay include RRC signaling and MAC CE signaling as described in<Embodiment 3-2>. This means that CSI-RS resources or configurationsindicated by K_(A), K_(B), K_(CA), or K_(CB) in FIG. 42 may depend ononly RRC configuration but may be activated or deactivated through MACconfiguration. In FIG. 42, RRC configuration is mainly described, butextension is possible to aggregation of RRC and the MAC CE like in<Embodiment 3-2>, so a detailed description thereof will be omitted.

Referring to FIG. 42, three types of higher layer signaling can beperformed in consideration of a non-precoded CSI-RS, a beamformedCSI-RS, and a hybrid CSI-RS. In this example, it is possible todesignate CSI-RS resource subsets to transmit the aperiodic CSI-RSthrough L1 signaling, and the CSI-RS resource subsets may be notified tothe UE through higher layer signaling as indicated by reference numeral4220. In reference numeral 4220, one or more CSI-RS resources may beallocated to set A to set X, and if two or more CSI-RS resources areallocated to one set, the allocated CSI-RS resources may be recognizedas a single CSI-RS resource. For example, if set A is designated asaperiodic CSI-RS resources through L1 signaling, the number of aperiodicCSI-RS ports assumed by the UE is a sum of the numbers of CSI-RS portsincluded in all CSI-RS resources belonging to set A. In <Embodiment3-2>, activation and deactivation by MAC CE signaling are one ofdetailed examples for configuring the CSI-RS resource subsets. If onlythe RRC and MAC CE configurations are provided and L1 signaling is notsupported as in the third example of <Embodiment 3-2>, the UE may assumethat all CSI-RSs belonging to set A to set X of the CSI-RS resourcesubsets are transmitted.

In the case of the non-precoded CSI-RS, higher layer signaling mayinclude signaling information 4120 like aperiodic CSI-RS configurationmethod 1. Specifically, the signaling information 4120 includes K_(A)CSI-RS configurations 4130 for configuring a plurality of CSI-RS portslarger than or equal to 8 CSI-RS ports and another detailedconfiguration information 4140. At this time, if the aperiodic CSI-RS istriggered through L1 signaling including a plurality of bits, it maymean that some configuration information of the information 4120 isignored, the ignored information is replaced with CSI-RS resourceconfiguration information designated by reference numeral 4220, and theaperiodic CSI-RS is transmitted in the corresponding RE. For example, ifthe aperiodic CSI-RS is triggered through 2-bit L signaling, theaperiodic CSI-RS may be transmitted with reference to [Table 42], [Table43], or [Table 44] above, or [Table 45] below. The purpose of [Table 42]to [Table 44] is as described above. In the case of [Table 45], if thebase station configures “00”, the UE may use the CRI to perform a reportwithout aggregating CSI-RS resources in which the aperiodic CSI-RS istransmitted. In another method, whether to transmit the aperiodic CSI-RSfor the CSI-RS configuration 4130 may be signaled through L1 signalingincluding K_(A) bits.

TABLE 45 Value of aperiodic CSI-RS field Description 00 Aperiodic CSI-RSand aperiodic CSI report are triggered for all CSI-RS resources 01Aperiodic CSI-RS and aperiodic CSI report are triggered for a 1st set ofCSI-RS resources configured by higher layers 10 Aperiodic CSI-RS andaperiodic CSI report are triggered for a 2nd set of CSI-RS resourcesconfigured by higher layers 11 Aperiodic CSI-RS and aperiodic CSI reportare triggered for a 3rd set of CSI-RS resources configured by higherlayers

In the case of the beamformed CSI-RS, higher layer signaling may includesignaling information 4150 like aperiodic CSI-RS configuration method 1.Specifically, the signaling information 4150 may include K_(B) CSI-RSresource configuration information to which different beams can beapplied, and CSI-RS resource configuration information 4160 may includeCSI-RS detailed configuration information. At this time, if theaperiodic CSI-RS is triggered through 1-bit L1 signaling including aplurality of bits, two methods below may be considered.

A first method is to signal whether to transmit the aperiodic CSI-RS foreach of the CSI-RS resource configuration information 4160 through L1signaling including K_(B) bits. This is a most flexible method butrequires high L1 signaling overhead. A second method is to receiveaperiodic CSI-RS configuration information with reference toconfiguration information 4220 through L1 signaling including a smallernumber of bits in order to reduce L1 signaling overhead. For example,the aperiodic CSI request field may be used as aperiodic CSI-RSconfiguration information on the basis of [Table 42], [Table 43], or[Table 44], or a new table like [Table 45] may be introduced. Since adetailed description thereof is similar to the examples above, thedescription will be omitted.

In the case of the hybrid CSI-RS, higher layer signaling may includesignaling information 4170 like aperiodic CSI-RS configuration method 1.Specifically, the signaling information 4170 may include two parts suchas a part 4180 including K_(CA) CSI-RS configurations for configuring aplurality of CSI-RS ports and a part 4190 including K_(CB) pieces ofCSI-RS resource configuration information to which different beams canbe applied. For example, the part 4180 may be similar to referencenumeral 4120, and the part 4190 may be similar to reference numeral4150. At this time, if the aperiodic CSI-RS is triggered through 1-bitL1 signaling including a plurality of bits, two methods below may beconsidered.

A first method is to signal whether to transmit the aperiodic CSI-RS foreach of the CSI-RS resource configuration information 4170 through L1signaling including K_(CA)+K_(CB) or 1+K_(CB) bits. If L1 signalingincludes 1+K_(CB) bits, CSI-RS configurations included in the part 4180may determine whether to transmit the aperiodic CSI-RS as one group.This is a most flexible method but requires high L signaling overhead. Asecond method is to receive aperiodic CSI-RS configuration informationwith reference to configuration information 4220 through L1 signalingincluding a smaller number of bits in order to reduce L1 signalingoverhead. For example, the aperiodic CSI request field may be used asaperiodic CSI-RS configuration information on the basis of [Table 42],[Table 43], or [Table 44], or a new table like [Table 45] may beintroduced. Since a detailed description thereof is similar to theexamples above, the description will be omitted.

-   -   Aperiodic CSI-RS configuration method 3

A third method corresponds to aperiodic CSI-RS configuration throughhigher layer signaling and L1 signaling including a plurality of bits.In this example, higher layer-signaled CSI-RS resource configurationinformation for the aperiodic CSI-RS is as illustrated in FIG. 41. Atthis time, higher layer signaling may include RRC signaling and MAC CEsignaling as described in <Embodiment 3-2>. This means that CSI-RSresources or configurations indicated by K_(A), K_(B), K_(CA), or K_(CB)in FIG. 41 may depend on only RRC configuration but may be activated ordeactivated through MAC configuration. In FIG. 41, RRC configuration ismainly described, but extension is possible to aggregation of RRC andthe MAC CE like in <Embodiment 3-2>, so a detailed description thereofwill be omitted.

Referring to FIG. 41, three types of higher layer signaling can beperformed in consideration of CSI-RS types such as a non-precodedCSI-RS, a beamformed CSI-RS, and a hybrid CSI-RS. In the example,similar to aperiodic CSI-RS configuration method 1, the aperiodic CSI-RScan be triggered using 1-bit or 2-bit L1 signaling. A difference betweenthe example and aperiodic CSI-RS configuration method 1 will bedescribed. In the example, reconfiguration of “the number of CSI-RSports” in detailed configuration information of the aperiodic CSI-RS ispossible, and therefor, the conventional L1 signaling such as the CSIrequest field may be reused as shown in [Table 46] or [Table 47] belowor new L signaling may be introduced as shown in [Table 48] or [Table49] below.

[Table 46] is a table indicating a method by which the UE analyzes theCSI request field when the aperiodic CSI-RS is triggered by 1-bit L1signaling. Similar to aperiodic CSI-RS configuration method 1, the UEmay assume that the aperiodic CSI-RS is transmitted in CSI-RS resourcesfor a non-precoded CSI-RS, the aperiodic CSI-RS is transmitted in CSI-RSresources corresponding to recently reported CSI among CSI-RS resourcesfor a beamformed CSI-RS, or the aperiodic CSI-RS is transmitted inCSI-RS resources for a UE-specific beamformed CSI-RS (in this case, oneCSI-RS resource is configured in the UE). The UE may identify CSI-RSconfiguration in each piece of CSI-RS resource configuration informationaccording to the condition.

Thereafter, the UE may know how many CSI-RS ports are transmitted in thecorresponding CSI-RS resources according to 1 bit and the CSI requestfield value for triggering the aperiodic CSI-RS triggering configured bythe base station. For example, the number of CSI-RS ports may be 1 ifthe CSI request field is 00, may be 2 if the CSI request field is 01,may be 4 if the CSI request field is 10, and may be 8 if the CSI requestfield is 11. Thereafter, the UE can analyze the RE location at which theaperiodic CSI-RS is transmitted by combining the CSI-RS configurationand the number of CSI-RS ports. The method of analyzing the CSI requestfield is an example, and other various numbers may be RRC-signaled. Forexample, if the CSI request field is 00, the number of CSI-RS portswhich is RRC-signaled while being inserted into the conventional CSI-RSresource configuration is reused. Otherwise, the number of CSI-RS portsmay be analyzed as 1 if the CSI request field is 01, analyzed as 2 ifthe CSI request field is 10, and analyzed as 4 if the CSI request fieldis 11.

TABLE 46 Value of CSI request field Description 00 Aperiodic CSI-RS andaperiodic CSI report are triggered with a 1st candidate of the number ofCSI-RS ports (configured by higher layers) 01 Aperiodic CSI-RS andaperiodic CSI report are triggered with a 2nd candidate of the number ofCSI-RS ports (configured by higher layers) 10 Aperiodic CSI-RS andaperiodic CSI report are triggered with a 3rd candidate of the number ofCSI-RS ports (configured by 11 Aperiodic CSI-RS and aperiodic CSI reportare triggered with a 4th candidate of the number of CSI-RS ports(configured by higher layers)

[Table 47] is a table indicating a method by which the UE analyzes theCSI request field when the CSI request field is configured to be usedfor triggering the aperiodic CSI-RS by 1-bit RRC signaling. Similar toaperiodic CSI-RS configuration method 1, the CSI request field may beconfigured to be used for triggering the aperiodic CSI-RS by 1-bit RRCsignaling, and the UE may assume that the aperiodic CSI-RS istransmitted in CSI-RS resources for the non-precoded CSI-RS, theaperiodic CSI-RS is transmitted in CSI-RS resources corresponding to therecently reported CRI among CSI-RS resources for the beamformed CSI-RS,or the aperiodic CSI-RS is transmitted in CSI-RS resources for theUE-specific beamformed CSI-RS (in this case, one CSI-RS source isconfigured in the UE).

The UE may identify CSI-RS configuration in each piece of CSI-RSresource configuration information according to the condition.Thereafter, the UE may know if the aperiodic CSI-RS is transmitted inthe corresponding CSI-RS resources through the CSI request field valueconfigured by the base station, and if the aperiodic CSI-RS istransmitted, know how many CSI-RS ports are transmitted. For example, ifthe CSI request field is 00, it means that no aperiodic CSI-RS istransmitted. The number of CSI-RS ports may be analyzed as 1 if the CSIrequest field is 01, analyzed as 2 if the CSI request field is 10, andanalyzed as 4 if the CSI request field is 11. Thereafter, the UE cananalyze the RE location at which the aperiodic CSI-RS is transmitted bycombining the CSI-RS configuration and the number of CSI-RS ports.

The method of analyzing the CSI request field is one example, and aspecific value may be defined in a table but various numbers may beRRC-signaled. For example, if the CSI request field is 00, it means thatno aperiodic CSI-RS is transmitted. If the CSI request field is 01, thenumber of CSI-RS ports which is RRC-signaled while being inserted intothe conventional CSI-RS resource configuration information is reused.The number of CSI-RS ports may be analyzed as 1 if the CSI request fieldis 10 and analyzed as 2 if the CSI request field is 11.

TABLE 47 Value of CSI request field Description 00 No aperiodic CSI-RSand aperiodic CSI reporting are triggered 01 Aperiodic CSI-RS andaperiodic CSI report are triggered with a 1st candidate of the number ofCSI-RS ports (configured by higher layers) 10 Aperiodic CSI-RS andaperiodic CSI report are triggered with a 2nd candidate of the number ofCSI-RS ports (configured by higher layers) 11 Aperiodic CSI-RS andaperiodic CSI report are triggered with a 3rd candidate of the number ofCSI-RS ports (configured by higher layers)

In another method, the number of CSI-RS ports included in aperiodicCSI-RS resources may be notified by additional L1 signaling. [Table 48]and [Table 49] are tables indicating examples of configuring the numberof aperiodic CSI-RS ports by L1 signaling. Similar to aperiodic CSI-RSconfiguration method 1, the UE may assume that the aperiodic CSI-RS istransmitted in CSI-RS resources for a non-precoded CSI-RS, the aperiodicCSI-RS is transmitted in CSI-RS resources corresponding to recentlyreported CSI among CSI-RS resources for a beamformed CSI-RS, or theaperiodic CSI-RS is transmitted in CSI-RS resources for a UE-specificbeamformed CSI-RS (in this case, one CSI-RS resource is configured inthe UE). At this time, the UE may identify CSI-RS configuration in eachpiece of CSI-RS resource configuration information according to thecondition.

Thereafter, when the aperiodic CSI-RS is triggered, the UE may know howmany CSI-RS ports are transmitted in the corresponding aperiodic CSI-RSresources according to the aperiodic CSI-RS field value as shown in[Table 48] or [Table 49]. In the example of [Table 48], the number ofCSI-RS ports according to the aperiodic CSI-RS field value may bepredetermined by the aperiodic CSI-RS field table. For example, thenumber of CSI-RS ports may be analyzed as 1 if the CSI request field is00, analyzed as 2 if the CSI request field is 01, analyzed as 4 if theCSI request field is 10, and analyzed as 8 if the CSI request field is11. Thereafter, the UE can analyze the RE location at which theaperiodic CSI-RS is transmitted by combining the CSI-RS configurationand the number of CSI-RS ports.

The method of analyzing the aperiodic CSI-RS field is one example, andthe specific number may be defined in the table as shown in [Table 48]but various numbers may be RRC-signaled as shown in [Table 49]. Forexample, if the CSI request field is 00, the number of CSI-RS portswhich is RRC-signaled while being inserted into the conventional CSI-RSresource configuration is reused. The number of CSI-RS ports may beanalyzed as 1 if the CSI request field is 01, analyzed as 2 if the CSIrequest field is 10, and analyzed as 4 if the CSI request field is 11.

Similar to the examples of [Table 48] and [Table 49], [Table 50] belowmay be used in consideration of the coexistence of the periodic CSI-RSand the aperiodic CSI-RS. Through [Table 50], an aperiodic CSI reportbased on the periodic CSI-RS and an aperiodic CSI report based on theaperiodic CSI-RS may be individually turned on/off.

TABLE 48 Value of aperiodic CSI-RS field Description 00 Aperiodic CSI-RSresource contains 1 port CSI-RS 01 Aperiodic CSI-RS resource contains 2port CSI-RS 10 Aperiodic CSI-RS resource contains 4 port CSI-RS 11Aperiodic CSI-RS resource contains 8 port CSI-RS

TABLE 49 Value of aperiodic CSI-RS field Description 00 Aperiodic CSI-RSresource contains A port CSI-RS and A is configured by higher layers 01Aperiodic CSI-RS resource contains B port CSI-RS and B is configured byhigher layers 10 Aperiodic CSI-RS resource contains C port CSI-RS and Cis configured by higher layers 11 Aperiodic CSI-RS resource contains Dport CSI-RS and D is configured by higher layers

TABLE 50 Value of aperiodic CSI-RS field Description 00 No aperiodicCSI-RS resource is triggered 01 Aperiodic CSI-RS resource contains Aport CSI-RS and A is configured by higher layers 10 Aperiodic CSI-RSresource contains B port CSI-RS and B is configured by higher layers 11Aperiodic CSI-RS resource contains C port CSI-RS and C is configured byhigher layers

Embodiment 3-4

<Embodiment 3-4> describes a rate mapping method according to aperiodicCSI-RS transmission. In LTE-A and LTE-A Pro systems, the UE may identifynon-zero power (NZP) CSI-RS configuration information and zero power(ZP) CSI-RS configuration information to identify PDSCH RE mapping andperform rate matching. In the conventional CSI-RS transmission, CSI-RStransmission information is semi-statically configured, so thatadditional signaling for rate matching is not needed. However, if theaperiodic CSI-RS transmission proposed by the disclosure is introduced,whether to perform CSI-RS transmission and some pieces of CSI-RSconfiguration information may be dynamically changed, and thus a methodfor efficient rate matching is required. The present embodiment providesthe following three methods as the rate matching method considering theaperiodic CSI-RS.

-   -   Rate matching method 1 for aperiodic CSI-RS

A first method is a method of performing rate matching based onRRC-signaled CSI-RS resource configuration information and ZP CSI-RSconfiguration. As described in the embodiments, as the method of theaperiodic CSI-RS transmission, the conventional CSI-RS subframesdesignated through CSI-RS resource configuration information areconsidered as an aperiodic CSI-RS resource pool and a subframe in whichthe actual aperiodic CSI-RS is transmitted is notified to the UE throughL1 signaling such as UL grant. The first method is a method ofperforming rate matching on the assumption that the UE considers thatCSI-RS subframes other than a CSI-RS subframe allocated to the UE itselfare allocated to other UEs. If the first method is used, a rate matchingmechanism is simple, but if the number of UEs is small, datatransmission efficiency may decrease more than needs.

-   -   Rate matching method 2 for aperiodic CSI-RS

A second method is a method of performing rate matching based onRRC-signaled CSI-RS resource configuration information, ZP CSI-RSconfiguration, L1-signaled aperiodic CSI-RS triggering, and a CSIrequest field. If the aperiodic CSI-RS is triggered on the assumptionthat whether aperiodic CSI-RS triggering is performed is determined by1-bit L1 signaling, the UE can interpret aperiodic CSI-RS configurationinformation according to [Table 42] to [Table 50] as described above.

Meanwhile, even though the aperiodic CSI-RS is not triggered, the UE caninterpret aperiodic CSI-RS configuration information according to [Table42] to [Table 50] and recognize the corresponding CSI-RS resources asaperiodic ZP CSI-RSs or aperiodic interference measurement resources(IMR). This is to aperiodically perform rate matching according towhether aperiodic CSI-RS transmission is performed. If the aperiodicCSI-RS for the corresponding UE does not currently exist, it is possibleto provide information on whether an aperiodic CSI-RS for another UEexists, and if the aperiodic CSI-RS exists, provide an RE in which theaperiodic CSI-RS exists through the method.

According to the example, methods of analyzing a CSI request field or anaperiodic CSI field in the cases in which the aperiodic CSI-RS istriggered and is not triggered do not need to be the same. For example,the method follows [Table 42] if the aperiodic CSI-RS is triggered andfollows [Table 50] if the aperiodic CSI-RS is not triggered. This isbecause there is no need to inform that the aperiodic CSI-RS does notexists if the aperiodic CSI-RS is triggered but there is a need toinform another UE as well as the corresponding UE that the aperiodicCSI-RS does not exists if the aperiodic CSI-RS is not triggered.

-   -   Rate matching method 3 for aperiodic CSI-RS

A third method is a method of performing rate matching based onRRC-signaled CSI-RS resource configuration information, ZP CSI-RSconfiguration, RRC-signaled aperiodic CSI-RS triggering, and a CSIrequest field. It is assumed that it is determined whether to use a CSIrequest field for aperiodic CSI-RS triggering or an aperiodic CSI-RSfield by 1-bit RRC signaling and also assumed that both the CSI requestfield and the aperiodic CSI-RS field are signaled to the UE forconvenience of description. At this time, if the aperiodic CSI-RS fieldis as shown in [Table 50], the aperiodic CSI-RS field may be interpretedas aperiodic NZP CSI-RS resource information when the CSI request fieldhas a value other than 00, that is, when aperiodic CSI is triggered. Onthe other hand, when the CSI request field is 00, that is, when theaperiodic CSI is not triggered, the aperiodic CSI RS field may beinterpreted as aperiodic ZP CSI-RS resources or aperiodic IMRinformation. In other words, by synthetically interpreting the CSIrequest field and the aperiodic CSI-RS field, it is possible to supportdynamic rate matching for not only the NZP CSI-RS but also the ZPCSI-RS.

Embodiment 3-5

<Embodiment 3-5> proposes a method of configuring aperiodic CSI-RStransmission bandwidth. In the above embodiments, the method ofconfiguring resources for aperiodic CSI-RS transmission in one or moreCSI-RS resources and the method of determining transmission timing havebeen described. Meanwhile, in order to maximize efficiency of aperiodicCSI-RS transmission efficiency, it is very important to manage anaperiodic CSI-RS transmission bandwidth. For example, in the LTE system,the UE determines a channel bandwidth which the corresponding UE shouldsupport according to an E-UTRA band supported by the UE. Referring to[Table 51] below, the UE should support channel bandwidths of {1.4, 3,5, 10, 15, 20} MHz if the UE supports E-UTRA band 2, and should supportchannel bandwidths of {5, 10} MHz if the UE supports E-UTRA band 6. Thatis, the LTE system does not separately support a UE-specific maximumbandwidth, and a channel bandwidth may vary depending on the servicesuch as MTC, eMTC, or NB-IoT.

TABLE 51 E-UTRA band/Channel bandwidth E-UTRA Band 1.4 MHz 3 MHz 5 MHz10 MHz 15 MHz 20 MHz 1 Yes Yes Yes Yes 2 Yes Yes Yes Yes Yes1 Yes1 3 YesYes Yes Yes Yes1 Yes1 4 Yes Yes Yes Yes Yes Yes 5 Yes Yes Yes Yes1 6 YesYes1 7 Yes Yes Yes3 Yes1, 3 8 Yes Yes Yes Yes1 9 Yes Yes Yes1 Yes1 . . .

On the other hand, the NR system may support different UE bandwidthsaccording to each UE due to various factors such as the coexistence ofvarious verticals such as eMBB, URLLC, and mMTC within the same band,and a low cost eMBB UE. Accordingly, UEs having different maximum UEbandwidths may coexist within a wide system bandwidth, and supportingall of them through a wideband aperiodic CSI-RS may waste resources. Inorder to solve the problem, the present embodiment provides methods ofmanaging an aperiodic CSI-RS transmission bandwidth.

In the NR system, RRC configuration for the CSI-RS may include timinginformation such as a CSI-RS transmission period and a time offset. Thetime offset may include one or more values of a slot offset for aperiodic CSI-RS or a semi-persistent CSI-RS and a triggering offset foran aperiodic CSI-RS. The triggering offset includes information on atime difference to actual transmission after aperiodic CSI-RStransmission is triggered through DCI. In aperiodic CSI-RS transmission,the timing information may be ignored. For example, in the case of theaperiodic CSI-RS, the UE may ignore the transmission period and theoffset value and may identify whether the aperiodic CSI-RS transmissionis performed through DCI reception timing including aperiodic CSI-RStransmission information.

Further, in the NR system, RRC configuration for the CSI-RS may includetransmission band information such as a CSI-RS transmission bandwidth, afrequency offset, and an RB or subband location. The frequency offsetmay be an offset in units of PRBs based on a PRB including a downlink oruplink DC subcarrier or based on a scheduled PDSCH or an offset in unitsof subbands including a plurality of PRBs. As described above, CSI-RStransmission band information configured through RRC is suitable forsemi-static management of the CSI-RS transmission band but a dynamicchange in the CSI-RS transmission band is not possible. The followingmethods may be considered for the dynamic CSI-RS transmission bandconfiguration and change.

A first method is to dynamically change the CSI-RS transmission bandthrough CSI-RS frequency hopping. The base station and the UE may sharepredetermined frequency hopping patterns and determine the location offrequency resources of the CSI-RS transmitted in a narrow band (subband)according to a particular rule, L1 (DCI), or L2 (MAC CE or RRC)signaling. The frequency hopping timing may be defined as an absolutevalue by the slot or subframe location or defined as a relative value byDCI including an aperiodic CSI-RS trigger. For example, if the hoppingtiming is defined as an absolute value, the subband location for CSI-RStransmission may vary depending on a slot or subframe index regardlessof the aperiodic CSI-RS triggering. On the other hand, if the hoppingtiming is defined as a relative value, the subband location for CSI-RStransmission varies depending on the aperiodic CSI-RS triggering. In thedisclosure, the subband for CSI-RS transmission may be determined by ahopping pattern type and the control of transmission timing, but oncethe hopping pattern is determined, it takes a lot of time to change thehopping pattern and thus a degree of freedom of subband configuration islimited.

A second method is a subband/wideband transmission indication through L1(DCI) or MAC CE signaling or subband/wideband switching signaling. Themethod of the disclosure supports dynamic signaling (L1 or MACE CE) forchanging the CSI-RS transmission band information configured throughRRC.

FIG. 43 illustrates an example of the second method for configuring andchanging the CSI-RS transmission band. In FIG. 43, DCI is transmitted ina common search space (CSS) or a UE-specific search space (USS) definedin control resource sets (CORESETs) 4305, 4320, 4330, and 4340configured in the UE may indicate whether aperiodic CSI-RSs 4315, 4325,4335, and 4345 are transmitted and frequency and/or time resourceindexes. In addition to this, the DCI includes transmission band changesignaling indicating whether the corresponding aperiodic CSI-RS istransmitted in a subband 4315 or 4325 or a wideband 4335 or 4345. Thetwo pieces of information may be joint-encoded but it is assumed thatthe two piece of information are independently encoded for convenienceof description below.

If the transmission band change signaling means subband transmission,the corresponding aperiodic CSI-RS transmission band is the same as thebandwidth of the CORESET as indicated by reference numeral 4315 or thecorresponding aperiodic CSI-RS transmission band is the same as aconfigured PDSCH transmission band 4310 as indicated by referencenumeral 4325. If the transmission band change signaling means widebandtransmission, the corresponding aperiodic CSI-RS transmission band isthe same as a CSI-RS transmission band configured through RRC asindicated by reference numeral 4335, or the corresponding aperiodicCSI-RS transmission band is the same as a system bandwidth or, if thesystem bandwidth is divided into a plurality of bandwidth parts, is thesame as a band corresponding to the bandwidth part as indicated byreference numeral 4345.

Similarly, the transmission band change signaling may be used as anindicator indicating whether to use the CSI-RS transmission bandconfigured through RRC or perform wideband CSI-RS transmissioncorresponding to the system bandwidth, the bandwidth part, or the UEbandwidth.

FIG. 44 illustrates a process of performing bandwidth adaptation of theUE through transmission band changing signaling. The base station mayschedule a PDSCH 4410 within a UE bandwidth 4412 through DCI transmittedin a CORESET 4405 and trigger an aperiodic CSI-RS 4415. At this time,the base station may instruct the UE to use a CSI-RS transmission bandconfigured through RRC via the transmission band change signaling(configured as 0). In reference numeral 4415, it is assumed that theCSI-RS transmission band configured through RRC is the same as theCORESET band.

Meanwhile, if the base station desires to allocate the PDSCH of the UEto a wider band as indicated by reference numeral 4440, the base stationmay need CSI for the band wider than the band 4415. Accordingly, thebase station configures the transmission band change signal (as 1) suchthat the UE receives the wideband aperiodic CSI-RS 4425 through DCItransmitted in the CORESET 4420. The UE may receive the CSI-RS 4425,generate CSI, and then report the generated CSI to the base station, andthe base station may perform scheduling through the CSI. The basestation may allocate and transmit the PDSCH 4440 of the wide band to theUE through DCI transmitted in a CORESET 4430 to the UE on the basis ofthe scheduling result.

Similarly, the transmission band change signaling may be used as anindicator indicating whether to use the CSI-RS transmission bandconfigured through RRC or whether to match the most recently configureddownlink bandwidth with the CSI-RS transmission band. Since a detaileddescription thereof is similar to that of FIGS. 43 and 44, it will beomitted.

Although it is illustrated and described that the UE has a singleCORESET in the description and drawings, this is only for convenience ofdescription, and the description can be extended and applied to the casein which the UE has a plurality of CORESETs. In the above description,the CORESET may be replaced with a UE bandwidth or a bandwidth partseparately configured from a control channel and the same methods can beapplied thereto. Since a detailed description thereof is similar to theexamples, it will be omitted.

The description and drawing are an example of the case in which theaperiodic CSI-RS is transmitted in a single resource and correspond to amethod of supporting an aperiodic CSI-RS transmission band changethrough signaling of small payload (1 bit is used in the simplestexample). Meanwhile, if the aperiodic CSI-RS is transmitted in aplurality of resources, the examples can be extended through thefollowing two methods. A first method is to apply the same transmissionband change signaling to a plurality of CSI-RS resources. In this case,there is no additional DCI payload increase but a degree of freedom ofthe CSI-RS transmission band configuration is reduced. A second methodis to support CSI-RS resource-specific or resource group-specifictransmission band change signaling. In this case, DCI payload increasesaccording to the number of simultaneously transmitted aperiodic CSI-RSresources, but the degree of freedom of CSI-RS transmission bandconfiguration increases. If the second method is applied, the number ofsimultaneously transmitted aperiodic CSI-RS resources is limited to 2 or3.

Although it is described and illustrated that the DCI including theaperiodic CSI-RS triggering and the transmission band change signalingand the corresponding aperiodic CSI-RS are transmitted in the same slotin the description and drawing, this is only for convenience ofdescription, and it is apparent that they can be transmitted in one ormore slots according to CSI-RS transmission timing information.

Embodiment 3-6

<Embodiment 3-6> provides a method of configuring an aperiodic CSI-RStransmission band for acquiring CSI of a control channel. In this case,the transmission band change signaling can be understood as controlchannel CSI triggering signaling.

FIG. 45 illustrates a process of controlling aperiodic CSI-RStransmission and reception bands through control channel CSI triggeringsignaling. The base station may schedule a PDSCH 4505 within a UEbandwidth 4515 through DCI transmitted in a CORESET 4510 and trigger anaperiodic CSI-RS 4520. At this time, the base station may instruct theUE to use the CSI-RS transmission band configured through RRC via thecontrol channel CSI triggering signaling (configured as 0). This is togenerate CSI for the PDSCH by the UE, and the UE generate required CSIsuch as CQI, PMI, RI, and CRI in consideration of a transmissionenvironment for the PDSCH (channel coding using low density parity checkcode (LDPC), {4-1024} modulation order, and PDSCH transport block size(TBS)). In reference numeral 4520, it is assumed that the CSI-RStransmission band configured through RRC is the same as a band in whichthe PDSCH is scheduled.

Meanwhile, if the base station requires CSI for a control channel, thebase station configures control channel CSI triggering signaling (as 1)such that the UE receives CSI-RSs 4530 and 4540 for generating thecontrol channel CSI through DCI transmitted in a CORESET 4525. At thistime, configuring control channel CSI triggering signaling such that theUE receives the CSI-RSs 4530 and 4540 for generating the control channelCSI may mean changing the actual CSI-RS transmission band as indicatedby reference numeral 4530 but mean changing only a reception window ofthe UE as indicated by reference numeral 4545 without changing theactual CSI-RS transmission band as indicated by reference numeral 4540.Thereafter, the UE receives the CSI-RS 4530 or 4545, generate CSI for aPDCCH, and generate required CSI such as CQI, PMI, RI, and CRI inconsideration of a transmission environment for the PDCCH (channelcoding using polar code, 4-QAM modulation order, and PDCCH payloadsize). The base station may perform scheduling on the PDSCH and thePDCCH therethrough.

Although it is illustrated and described that the UE has a singleCORESET in the description and drawings, this is only for convenience ofdescription, and the description can be extended and applied to the casein which the UE has a plurality of CORESETs. In the above description,the CORESET may be replaced with a UE bandwidth or a bandwidth partseparately configured from a control channel and the same methods can beapplied thereto. Since a detailed description thereof is similar to theexamples, it will be omitted.

The description and drawing are an example of the case in which theaperiodic CSI-RS is transmitted in a single resource and correspond to amethod of supporting an aperiodic CSI-RS transmission band changethrough signaling of small payload (1 bit is used in the simplestexample). Meanwhile, if the aperiodic CSI-RS is transmitted in aplurality of sources, the examples can be extended through the followingtwo methods. A first method is to apply the same transmission bandchange signaling to a plurality of CSI-RS resources. In this case, thereis no additional DCI payload increase but a degree of freedom of theCSI-RS transmission band configuration is reduced. A second method is tosupport CSI-RS resource-specific or resource group-specific transmissionband change signaling. In this case, DCI payload increases according tothe number of simultaneously transmitted aperiodic CSI-RS resources, butthe degree of freedom of CSI-RS transmission band configurationincreases. If the second method is applied, the number of simultaneouslytransmitted aperiodic CSI-RS resources is limited to 2 or 3.

Although it is described and illustrated that the DCI including theaperiodic CSI-RS triggering and the transmission band change signalingand the corresponding aperiodic CSI-RS are transmitted in the same slotin the description and drawing, this is only for convenience ofdescription, and it is apparent that they can be transmitted in one ormore slots according to CSI-RS transmission timing information.

Embodiment 3-7

<Embodiment 3-5> and <embodiment 3-6> mainly describe the control of thetransmission band for an NZP CSI-RS. Meanwhile, a ZP CSI-RS playsvarious roles such as performing PDSCH rate matching by emptying aCSI-RS resource part from another cell (or beam or TRP), measuringinterference from another cell (or beam or TRP), or performing NZPCSI-RS power boosting, and thus it may be important to handle thecontrol of the ZP CSI-RS transmission band. <Embodiment 3-7> proposes amethod of controlling the ZP CSI-RS transmission band.

FIG. 46 illustrates a process of controlling aperiodic ZP CSI-RStransmission and reception bands. The base station may schedule a PDSCH4605 within a UE bandwidth 4615 through DCI transmitted in a CORESET4610 and trigger an aperiodic CSI-RS 4620. It is assumed that theaperiodic CSI-RS transmission band is configured to be the same as aCORESET transmission band of the corresponding UE. Meanwhile, a PDSCH4640 of the UE may overlap other subband period CSI-RS resources 4625which the UE does not receive (which are not transmitted from a servingcell or a TRP). At this time, the CORESET of the UE receiving theaperiodic CSI-RS 4525 can be transmitted in a band different from theband in which the CORESET 4605 is transmitted, and accordingly thetransmission band 4625 may also be different from the band 4620.

In consideration of such a situation, the following two methods can beused to configure the ZP CSI-RS to correspond to reference numeral 4625.A first method is to manage the ZP CSI-RS transmission band byseparately supporting transmission band change signaling for the NZPNCSI-RS and transmission band change signaling for the ZP CSI-RS. Forexample, if the ZP CSI-RS transmission band configured through RRC isnot sufficient to cover reference numeral 4625, the base station mayconfigure a wideband area expressed as a system bandwidth, a bandwidthpart, or a bandwidth in which the PDSCH is scheduled as indicated byreference numeral 4630 instead of the ZP CSI-RS transmission bandconfigured through RRC via the ZP CSI-RS transmission band changesignaling. This somewhat increases overhead for the ZP CSI-RS, but hasan advantage of preventing a significant increase in transmission bandchange signaling overhead. In another example of the first method, ifthe ZP CSI-RS transmission band configured through RRC is not sufficientto cover reference numeral 4625, the base station may directly insert ZPCSI-RS transmission band information into the ZP CSI-RS transmissionband change signaling. In this case, the ZP CSI-RS transmission bandconfiguration 4635 may be the same as or similar to the NP CSI-RStransmission band configuration 4625, and thus ZP CSI-RS configurationoverhead may be optimized but transmission band change signalingoverhead may greatly increase.

A second method is to use the same transmission band change signalingboth for the NZP CSI-RS and the ZP CSI-RS in which case transmissionband change signaling may be joint-encoded together with one or all ofaperiodic NZP CSI-RS triggering signaling, aperiodic ZP CSI-RStriggering signaling, and resource selection signaling or independentlyencoded from aperiodic NZP CSI-RS triggering signaling, aperiodic ZPCSI-RS triggering signaling, and resource selection signaling. If theaperiodic NZP CSI-RS triggering signaling, the resource selectionsignaling, and the transmission band change signaling are joint-encoded,the aperiodic ZP CSI-RS bandwidth may be determined according torecently configured aperiodic NZP CSI-RS transmission bandwidthsignaling. If the aperiodic NZP CSI-RS triggering signaling, the ZPCSI-RS triggering signaling, the resource selection signaling, and thetransmission band change signaling are joint-encoded, the aperiodic ZPCSI-RS bandwidth is determined according to a joint encoding method. Ifthe aperiodic NZP CSI-RS triggering signaling, the ZP CSI-RS triggeringsignaling, the resource selection signaling, and the transmission bandchange signaling are independently encoded, the aperiodic ZP and NZPCSI-RS bandwidths may be independently determined according to encodedtransmission band change signaling.

Although it is illustrated and described that the UE has a singleCORESET in the description and drawings, this is only for convenience ofdescription, and the description can be extended and applied to the casein which the UE has a plurality of CORESETs. In the above description,the CORESET may be replaced with a UE bandwidth or a bandwidth partseparately configured from a control channel and the same methods can beapplied thereto. Since a detailed description thereof is similar to theexamples, it will be omitted.

The description and drawing are an example of the case in which theaperiodic CSI-RS is transmitted in a signal resource and correspond to amethod of supporting an aperiodic CSI-RS transmission band changethrough signaling of small payload (1 bit is used in the simplestexample). Meanwhile, if the aperiodic CSI-RS is transmitted in aplurality of sources, the examples can be extended through the followingtwo methods. A first method is to apply the same transmission bandchange signaling to a plurality of CSI-RS resources. In this case, thereis no additional DCI payload increase but a degree of freedom of theCSI-RS transmission band configuration is reduced. A second method is tosupport CSI-RS resource-specific or resource group-specific transmissionband change signaling. In this case, DCI payload increases according tothe number of simultaneously transmitted aperiodic CSI-RS resources, butthe degree of freedom of CSI-RS transmission band configurationincreases. If the second method is applied, the number of simultaneouslytransmitted aperiodic CSI-RS resources is limited to 2 or 3.

Although it is described and illustrated that the DCI including theaperiodic CSI-RS triggering and the transmission band change signalingand the corresponding aperiodic CSI-RS are transmitted in the same slotin the description and drawing, this is only for convenience ofdescription, and it is apparent that they can be transmitted in one ormore slots according to CSI-RS transmission timing information.

The examples in [Table 45] to [Table 50] may have different meaningsaccording to the definition of the “higher layer”. For example, if thehigher layer means only RRC signaling, the tables may mean a list ofRRC-signaled CSI-RSs. If the higher layer also means MAC CE signaling,the tables may mean activated CSI-RS resources by the MAC CE. Similarly,it is apparent that the meanings of the CSI-RS resource indicated by L1signaling may be changed. For example, if the higher layer means onlyRRC signaling, CSI-RS resources indicated by L1 signaling may mean alist of RRC-signaled CSI-RSs signaled. If the higher layer also meansMAC CE signaling, CSI-RS resources indicated by L1 signaling may meanactivated CSI-RS resources by the MAC CE.

If the aperiodic CSI-RS is transmitted according to an embodiment of thedisclosure, the operation of the base station will be described withreference to FIG. 47. FIG. 47 illustrates the operation of the basestation for transmitting an aperiodic CSI-RS. Referring to FIG. 47, thebase station configures at least one aperiodic CSI-RS through RRCsignaling in step 4700. At this time, RRC signaling may includetransmission band information of the aperiodic CSI-RSs. Thereafter, thebase station may configure resources to be activated or deactivatedamong the RRC-configured CSI-RSs through the higher layer (including theMAC CE) according to the embodiment proposed by the disclosure in step4710, if necessary. Further, the base station may trigger the aperiodicCSI-RS through L1 signaling and may indicate a change in theRRC-configured transmission band in step 4720. Thereafter, in step 4730,the base station transmits the aperiodic CSI-RS in aperiodic CSI-RSresources notified in steps 4700, 4710, and 4720.

According to an embodiment of the disclosure, the operation of the UEbased on the aperiodic CSI-RS will be described with reference to FIG.48. FIG. 48 illustrates the operation of the UE for receiving theaperiodic CSI-RS. Referring to FIG. 48, the UE receives semi-staticconfiguration information related to the aperiodic CSI-RS through higherlayer (RRC) signaling in step 4800. Thereafter, in step 4810, the UEreceives configuration information of resources to be activated ordeactivated among the RRC-configured CSI-RSs through higher layer(including the MAC CE) signaling if necessary according to theembodiment proposed by the disclosure. Further, the UE receives dynamicconfiguration information including aperiodic CSI-RS-relatedtransmission band change signaling through L1 signaling in step 4820.Thereafter, the UE receives the aperiodic CSI-RS in the correspondingCSI-RS resources on the basis of the aperiodic CSI-RS configurationinformation received in steps 4800, 4810, and 4820. Subsequently, the UEgenerates CSI information on the basis of the aperiodic CSI-RS receivedin step 4830 and reports the CSI information to the base station atpredetermined timing.

FIG. 49 is a block diagram illustrating an internal structure of the UEaccording to an embodiment of the disclosure.

Referring to FIG. 49, the UE includes a communication unit 4901 and acontroller 4902. The communication unit 4901 performs a function oftransmitting or receiving data to or from the outside (for example, thebase station). Here, the communication unit 4901 may transmit feedbackinformation to an base station under the control of the controller 4902.

The controller 4902 controls statuses and operations of all elements inthe UE. Specifically, the controller 4902 generates feedback informationaccording to information allocated by the base station. Also, thecontroller 4902 may control the communication unit 4901 to feed backgenerated channel information to the base station on the basis of timinginformation allocated by the base station. To this end, the controller4902 may include a channel estimator 4903.

The channel estimator 4903 may determine required feedback informationthrough a CSI-RS and feedback allocation information received from thebase station, and estimate a channel using the received CSI-RS based onthe feedback information

Although FIG. 49 has described the example in which the UE includes thetransceiver 4901 and the controller 4902, the UE is not limited theretoand may further include various elements based on a function executed inthe UE. For example, the UE may further include a display for displayingthe current status of the UE, an input unit for inputting a signal toperform a function by the user, and a storage unit for storing generateddata in the UE.

Also, it is illustrated that the channel estimator 4903 is included inthe controller 4902, but is not be limited thereto. The controller 4902may control the transceiver 4901 to receive configuration informationassociated with each of at least one reference signal resource from thebase station. Also, the controller 4902 may measure at least onereference signal and control the transceiver 4901 to receive, from thebase station, feedback configuration information for generating feedbackinformation based on the measurement result.

The controller 4902 may measure at least one reference signal receivedthrough the transceiver 4901, and may generate feedback informationbased on the feedback configuration information. The controller 4902 maycontrol the transceiver 4901 to transmit, to the base station, thegenerated feedback information at the feedback timing defined in thefeedback configuration information.

The controller 4902 may receive a CSI-RS periodically or aperiodicallytransmitted from the base station, generate feedback information on thebasis of the received CSI-RS, and transmit the generated feedbackinformation to the base station. At this time, the controller 4902 mayselect a precoding matrix with reference to the relation between antennaport groups of the base station.

The controller 4902 may receive the CSI-RS periodically or aperiodicallytransmitted from the base station, generate feedback information on thebasis of the received CSI-RS, and transmit the generated feedbackinformation to the base station. At this time, the controller 4902 mayselect one precoding matrix with reference to all antenna port groups ofthe base station. Also, the controller 4902 may receive feedbackconfiguration information from the base station, receive a periodicallyor aperiodically transmitted CSI-RS from the base station, generatefeedback information on the basis of the received feedback configurationinformation and the received CSI-RS, and transmit the generated feedbackinformation to the base station.

FIG. 50 is a block diagram illustrating an internal structure of thebase station according to an embodiment of the disclosure.

Referring to FIG. 50, the base station includes a controller 5002 and atransceiver 5001.

The controller 5002 controls statuses and operations of all elements inthe base station. Specifically, the controller 5002 may allocate CSI-RSresources for estimating a channel of the UE to the UE and allocatefeedback resources and feedback timing to the UE. To this end, thecontroller 5002 may further include a resource allocator 5003. Also, thecontroller 2210 may allocate a feedback configuration and the feedbacktiming to prevent a collision between feedbacks from multiple UEs andreceive and analyze configured feedback information at the correspondingtiming.

The transceiver 5001 may perform a function of transmitting andreceiving a reference signal and feedback information to and from theUE. Here, the transceiver 5001 may transmit a CSI-RS to the UE throughthe allocated resources and may receive feedback of channel informationfrom the UE under the control of the controller 5002.

Although it is illustrated that the resource allocator 5003 is includedin the controller 5001, it is not be limited thereto.

The controller 5002 may control the transceiver 5001 to transmit, to theUE, configuration information associated with each of at least onereference signal, or may generate the at least one reference signal.Also, the controller 5002 may control the transceiver 5001 to transmitfeedback configuration information for generating feedback informationbased on the measurement result to the UE.

The controller 5002 may control the transceiver 5001 to transmit the atleast one reference signal to the UE and receive feedback informationtransmitted from the UE at the feedback timing defined in the feedbackconfiguration information.

The controller 5002 may transmit the feedback configuration informationto the UE, periodically or aperiodically transmit a CSI-RS to the UE,and receive feedback information generated on the basis of the feedbackconfiguration information and the CSI-RS from the UE. In this instance,the controller 5002 may transmit feedback configuration informationcorresponding to each antenna port group of the base station, andadditional feedback configuration information based on the relationbetween antenna port groups. The controller 5002 may periodically oraperiodically transmit CSI-RSs beamformed on the basis of the feedbackinformation to the UE and receive the generated feedback informationfrom the UE on the basis of the CSI-RSs.

The invention claimed is:
 1. A method performed by a terminal in acommunication system, the method comprising: identifying a demodulationreference signal (DMRS) configuration type, the DMRS configuration typecorresponding to one of a first DMRS configuration type and a secondDMRS configuration type; receiving, from the base station, controlinformation indicating a DMRS port associated with a physical downlinkshared channel (PDSCH); and receiving, from the base station, a DMRSbased on the DMRS port, wherein the DMRS port belongs to one of twogroups in case that the DMRS configuration type corresponds to the firstDMRS configuration type, wherein the DMRS port belongs to one of threegroups in case that the DMRS configuration type corresponds to thesecond DMRS configuration type, and wherein a sequence for the DMRS ismapped to resource elements based on a time domain related parameter anda frequency domain related parameter corresponding to the DMRS port. 2.The method of claim 1, wherein DMRS ports indexing #0, #1, #4, #5 belongto a first group, and DMRS ports indexing #2, #3, #6, #7 belong to asecond group, for the first DMRS configuration type.
 3. The method ofclaim 1, wherein DMRS ports indexing #0, #1, #6, #7 belong to a firstgroup, DMRS ports indexing #2, #3, #8, #9 belong to a second group, andDMRS ports indexing #4, #5, #10, #11 belong to a third group, for thesecond DMRS configuration type.
 4. The method of claim 1, whereinsequences for DMRS ports belonging to a same group are mapped toresource elements orthogonally based on the time domain relatedparameter and the frequency domain related parameter corresponding toeach of the DMRS ports, on same resource elements.
 5. The method ofclaim 1, wherein information associated with the DMRS configuration typeis received via a higher layer signaling.
 6. A method performed by abase station in a communication system, the method comprising:identifying a demodulation reference signal (DMRS) configuration type,the DMRS configuration type corresponding to one of a first DMRSconfiguration type and a second DMRS configuration type; transmitting,to the terminal, control information indicating a DMRS port associatedwith a physical downlink shared channel (PDSCH); and transmitting, tothe terminal, DMRS based on the DMRS port, wherein the DMRS port belongsto one of two groups in case that the DMRS configuration typecorresponds to the first DMRS configuration type, wherein the DMRS portbelongs to one of three groups in case that the DMRS configuration typecorresponds to the second DMRS configuration type, and wherein asequence for the DMRS is mapped to resource elements based on a timedomain related parameter and a frequency domain related parametercorresponding to the DMRS port.
 7. The method of claim 6, wherein DMRSports indexing #0, #1, #4, #5 belong to a first group and DMRS portsindexing #2, #3, #6, #7 belong to a second group, for the first DMRSconfiguration type.
 8. The method of claim 6, wherein DMRS portsindexing #0, #1, #6, #7 belong to a first group, DMRS ports indexing #2,#3, #8, #9 belong to a second group and DMRS ports indexing #4, #5, #10,#11 belong to a third group, for the second DMRS configuration type. 9.The method of claim 6, wherein sequences for DMRS ports belonging to asame group are mapped to resource elements orthogonally based on thetime domain related parameter and the frequency domain related parametercorresponding to each of the DMRS ports, on same resource elements. 10.The method of claim 6, wherein information associated with the DMRSconfiguration type is transmitted via a higher layer signaling.
 11. Aterminal configured to operate in a communication system, the terminalcomprising: a transceiver; and a controller configured to: identify ademodulation reference signal (DMRS) configuration type, the DMRSconfiguration type corresponding to one of a first DMRS configurationtype and a second DMRS configuration type, receive, from the basestation via the transceiver, control information indicating a DMRS portassociated with a physical downlink shared channel (PDSCH), and receive,from the base station via the transceiver, a DMRS based on the DMRSport, wherein the DMRS port belongs to one of two groups in case thatthe DMRS configuration type corresponds to the first DMRS configurationtype, wherein the DMRS port belongs to one of three groups in case thatthe DMRS configuration type corresponds to the second DMRS configurationtype, and wherein a sequence for the DMRS is mapped to resource elementsbased on a time domain related parameter and a frequency domain relatedparameter corresponding to the DMRS port.
 12. The terminal of claim 11,wherein DMRS ports indexing #0, #1, #4, #5 belong to a first group andDMRS ports indexing #2, #3, #6, #7 belong to a second group, for thefirst DMRS configuration type.
 13. The terminal of claim 11, whereinDMRS ports indexing #0, #1, #6, #7 belong to a first group, DMRS portsindexing #2, #3, #8, #9 belong to a second group and DMRS ports indexing#4, #5, #10, #11 belong to a third group, for the second DMRSconfiguration type.
 14. The terminal of claim 11, wherein sequences forDMRS ports belonging to a same group are mapped to resource elementsorthogonally based on the time domain related parameter and thefrequency domain related parameter corresponding to each of the DMRSports, on same resource elements.
 15. The terminal of claim 11, whereininformation associated with the DMRS configuration type is received viaa higher layer signaling.
 16. A base station configured to operate in acommunication system, the base station comprising: a transceiver; and acontroller configured to: identify a demodulation reference signal(DMRS) configuration type, the DMRS configuration type corresponding toone of a first DMRS configuration type and a second DMRS configurationtype, transmit, to the terminal via the transceiver, a controlinformation indicating a DMRS port associated with a physical downlinkshared channel (PDSCH), and transmit, to the terminal via thetransceiver, DMRS based on the DMRS port, wherein the DRMS port belongsto one of two groups in case that the DMRS configuration typecorresponds to the first DMRS configuration type, wherein the DMRS portbelongs to one of three groups in case that the DMRS configuration typecorresponds to the second DMRS configuration type, and wherein asequence for the DMRS is mapped to resource elements based on a timedomain related parameter and a frequency domain related parametercorresponding to the DMRS port.
 17. The base station of claim 16,wherein DMRS ports indexing #0, #1, #4, #5 belong to a first group andDMRS ports indexing #2, #3, #6, #7 belong to a second group, for thefirst DMRS configuration type.
 18. The base station of claim 16, whereinDMRS ports indexing #0, #1, #6, #7 belong to a first group, DMRS portsindexing #2, #3, #8, #9 belong to a second group and DMRS ports indexing#4, #5, #10, #11 belong to a third group, for the second DMRSconfiguration type.
 19. The base station of claim 16, wherein sequencesfor DMRS ports belonging to a same group are mapped to resource elementsorthogonally based on the time domain related parameter and thefrequency domain related parameter corresponding to each of the DMRSports, on same resource elements.
 20. The base station of claim 16,wherein information associated with the DMRS configuration type istransmitted via a higher layer signaling.